


Inertia

by BonesOfBirdWings



Category: Harry Potter - J. K. Rowling
Genre: Additional Warnings In Author's Note, Alternate Universe - Canon Divergence, Gen, Mentor Severus Snape, Occlumency, Potions, Pre-Slash, Smart Harry Potter, Study of Ancient Runes (Harry Potter), Worldbuilding, not romance-centric at all, this is all just a thin fucking excuse for worldbuilding
Language: English
Status: In-Progress
Published: 2019-12-28
Updated: 2020-10-07
Packaged: 2021-02-27 00:47:35
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 6
Words: 21,925
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21998470
Author URL: https://archiveofourown.org/users/BonesOfBirdWings/pseuds/BonesOfBirdWings
Summary: The past weighs heavy on the shoulders of the future.Or: Harry and Snape begin to move forward.
Relationships: Harry Potter & Severus Snape, Harry Potter/Severus Snape
Comments: 80
Kudos: 306





	1. Impulse

**Author's Note:**

> SOME WARNINGS
> 
> FIRST: I have no idea how Harry & Snape's relationship is going to develop. I have a fondness for soft, gentle, slow build snarry, so this might turn into that. However, I can promise that nothing romantic will happen for a while, and more than likely nothing will happen in this fic. if anything, it would probably be in a sequel (if i even manage to finish this fic lol). In any case, I will warn extensively before that. 
> 
> EDIT - It's gonna be soft snarry, folks. the most recent chapter that i wrote was soft enough that I can't see it going another way now. Still, nothing romantic for quite a while still, etc. etc.
> 
> SECOND: This fic is not my top priority. i'm a grad student + my bnha longfic is more important to finish. however, i'm 20k+ words into this fic, so i thought i would start posting. updates will be sporadic. it might never be finished. i have no plan in mind. read this wip at your own risk.
> 
> tl;dr - will be Snarry far, far in the future, might not be finished in the near or far future. this is your official warning.

“Again,” Snape snarled, pointing his wand at Harry as the boy staggered to his feet. “Weak, weak, _weak_ , Potter. How do you expect to keep out the Dark Lord with your paltry abilities?” Before Harry could even catch his breath to reply, Snape cried out, “Legilimens!”

The basilisk rears its head, pleading for mercy in Parseltongue. Quirrell screams as he burns. Cedric drops dead, his sightless eyes wide in surprise. Harry had to see this again and again and again, his failures played out endlessly in the theatre of his skull. Anger burned in his gut, vicious and biting. He’d tried to learn, tried to “clear his mind”, but Snape was more interested in punishment than teaching.

He struggled enough that Snape finally deigned to let him go. The wavering vision of Snape’s office resolved itself in his view.

“Useless,” Snape spat at him. “Like your worthless father. Spoiled and pampered, unable to care about anyone other than yourself.” Harry felt his anger rise in him, smooth and slow, the steady creep of lava in his veins. He forced it down with the ease of long practice.

“I wonder,” Snape continued, his voice pitched low, his eyes shining with malice, “how many people your actions will kill.”

Harry’s anger suddenly leapt out of his control, burning deep and hot. He wanted to _rip and tear and kill_ –

“Legilimens,” intoned Snape, with a cruel smirk.

Harry was plunged back into the turbulent waters of his own mind. The fury blazed all around him. He felt Snape’s greasy fingers pluck at his memories, and he couldn’t take it anymore. Snape wanted to see his worst memories? Fine, then. Harry would show them to him.

He took the memory of second year, of the pain of basilisk venom ( _the burning in his blood, a thousand teeth clawing at his insides_ ), the fear of an agonizing death ( _is this what his life amounted to – pain and failure?_ ), the hatred of self-realization ( _they beg, both of them, Tom and the basilisk. He kills them both. What else is he capable of?_ ), the terror of helplessness ( _nothing nothing, he can do nothing_ ). He sunk deep into it, until all he could remember was terror and pain and hatred. He somehow wrapped it all up together with a thick ribbon of rage and _stabbed_ that awful, foreign presence with it.

The presence recoiled in pain. Harry laughed, flush with the high of success and vengeance.

The presence ( _Snape, he remembered distantly_ ) tried to grab at his memories again, this time with claws – reached out to slash and tear, but Harry wasn’t about to allow that.

He grabbed another memory, this one in first year. He is staring into Quirrell’s eyes as he burns him to death ( _murderer, murderer, no better than the shade on the back of Quirrell’s head_ ) and he has just talked to the man who killed his parents and he had agreed with him ( _there is no good and evil – because if there was, then Harry, freak, unwanted Harry, hateful Harry, angry Harry, almost-Slytherin Harry, would be evil. So there is only power, and people who use it to hurt, those who use it to help, and those who have none._ ) He speared the shadow in his mind with it. It cried out, hurt and surprised, and Harry reveled in it.

It had been hurting him, that much he remembered through the haze of ecstasy and rage. It had been hurting him, and it felt good to make it hurt in return.

As the shadow flailed around his mind, more memories reached out for it of their own volition. Harry caught snatches of them. Dudley and his Harry Hunting, Petunia and her sneer and the little, biting insults, Vernon and his fists, starvation, isolation, imprisonment.

It wasn’t enough. He wanted the shadow to suffer _more_.

He reached for his most painful memory, and he listened once again to his mother begging for his life ( _the fear that he wasn’t worth it, that she should have stepped aside_ ) and saw the flash of green light ( _no no please anything but this_ ) and watched her slump down to the floor, unmoving ( _mom where did you go, mom?_ ). He slammed it into the shadow, let all of the memory’s vicious, sharp blades tear into it. The shadow _screamed_ in pain.

It turned to flee, and Harry snarled. No, no, he wasn’t letting it go. He wasn’t satisfied, wasn’t done hurting it. He made a maze of memories, but the shadow flowed over them like water. He made a cage of his mind, but the shadow slipped through the bars. With a cry of frustration, Harry took his memories of confinement, of no-escape, of safety and imprisonment, and slammed them down around the shadow.

He was in his cupboard again, the place as dusty and as filled with cobwebs as he remembered. In front of him was Snape, looking worse for wear. His robes were lacerated and stained with blood. His nose was more crooked than usual, as if it had been re-broken. Bruises mottled his skin, and when he coughed wetly into his palm, Harry could see the blood flecked around his lips.

The haze of emotions fled from him, and he realized what had happened. He sunk down onto the grime-caked floor. After a few moments, Snape took a seat on the threadbare cot. Neither spoke.

When Snape coughed again, Harry crawled to the cot and rummaged around under it. He produced a tattered blanket, already stained. He handed it to Snape and then retreated to the other side of the cupboard.

Out of the corner of his eye, he saw Snape methodically wipe down his hands and face with the blanket, smearing it with more blood. He wasn’t yelling or snapping at Harry, which was both concerning and confusing. Harry couldn’t help but be wary of this suspiciously quiet Snape. He knew he should probably let them both go so that they could talk about this in the real world, but he was afraid of what Snape would do to him when they were outside of Harry’s mind. He had hurt Snape – he had very few doubts that Snape would find some way to make him hurt in the future.

When Snape finally spoke, it wasn’t what he expected. “You already have a visualization,” Snape said flatly. It didn’t sound like he wanted a response, but that he was just confirming something that he already knew. Harry stayed silent.

“Potter,” Snape said in a raspy voice, “is this… room truly the safest place you can imagine?”

Harry shot him a confused look. “What?” he asked, and he saw the start of a sneer on Snape’s face.

Without a thought, the blanket swarmed out of Snape’s hands and started to twist around Snape’s head. “Potter!” Snape snapped, wrestling with the fabric. “Control yourself!”

Harry concentrated, and the blanket returned to its previous quiescence. “Sorry,” he lied.

Snape huffed out an irritated breath. “As I was attempting to say before you saw fit to strangle me, the first goal of Occlumency is to establish a strong visualization of a safe place – a refuge, if you will. I was… surprised that you already seem to have one.”

Harry thought about it for a long moment. “I suppose it’s safe,” he replied finally. “No one else ever comes in.” Snape stared at him, an unreadable expression on his face. Harry didn’t like it, so he thought of another subject to distract Snape.

“Why didn’t we start with that, then?” Harry demanded. “Why’d we have to go through the whole ‘clear your mind’ stuff if this was what I was aiming for?”

“Because, you stupid boy,” Snape snarled, but that was as far as he got. The webs in the corner grew to three times their usual size, and humongous spiders scuttled out from under the cot. There was yelling filtering through the door. It sounded like Vernon and Petunia, but then the voices shifted and it was Quirrell, and then it was Snape himself, and then it was the sibilant voice of Voldemort. The spiders chittered at Snape, who had surged to his feet and retreated to Harry’s side of the cupboard.

“Stop it,” yelled Snape, competing with the Dark Lord’s taunts from outside the cupboard. “Potter, calm down!” There was a hint of real fear in his voice, and that, more than anything, made Harry close his eyes and take a deep breath. He pushed down the anger and the frustration and the terror, until he was calm and quiet inside.

He opened his eyes to find Snape staring at him again. The voices were quiet and the spiders were gone. “Don’t call me that,” he said lamely. “Boy, I mean. I don’t like it.”

Snape nodded. He was watching Harry the way people watched venomous snakes, uncertain of when they’d strike. “Most people,” he explained, without his usual vitriol, and more straightforward than he’d ever been with Harry, “when they clear their mind and then are attacked with Legilimency, retreat to a safe place, and this refuge can be utilized to construct a stable foundation on which to build the forts of Occlumency.”

“But I didn’t come here before,” Harry replied, confused. “You’re speaking like this place already existed.”

“Yes,” Snape answered with surprising patience. “It did. You have almost certainly retreated here mentally thousands of times.” He grimaced. “It is a veritable fortress. I could not break out of here without causing you extreme mental damage, and even then, I might leave with a shredded psyche. You’ve already accomplished… much, on that front.”

“So…” Harry looked cautiously at Snape. “That means I can do Occlumency?”

Snape gestured to himself, blood-stained and injured. “Obviously.”

“That was Occlumency?” Harry asked, surprised. From the way that Snape had talked about it, he had thought that it was a peaceful construction of shields, not… whatever it was that he had done to Snape.

“One type of it,” Snape elaborated. “Not the type I was trying to teach you, certainly. I thought you more suited for the most common method. But then, I did not know you had a visualization already.”

“That’s not my fault,” Harry replied sharply. “If you had just _explained_ what I was supposed to do –”

“Is it my duty to spoon-feed you, Potter?” Snape spat, reverting to his usual caustic behavior. Harry had known it was too good to last. “I am, thankfully, not your father, and thus your petulant, lazy approach to learning is not my problem to solve.”

“How exactly was I supposed to learn this, then?” Harry demanded. “There are no books on mind magic in the library – I checked. You didn’t provide any books. Neither did Dumbledore. Ron, Neville, and Hermione, the only people who can know I’m having these lessons, weren’t able to find any either. You’re the only person who can give me this information, sir, so yeah, I would say that in this case, it is your duty to spoon-feed me.”

Snape sneered at him. “You have been recalcitrant and unwilling to apply yourself in these lessons.”

Harry snorted. “I could say the same of you.”

Snape bared his crooked teeth at Harry, and advanced on him, fists clenched at his sides. Harry curled in on himself instinctively, the vision of an angry adult man here, in this cupboard under the stairs, stirring some old terror to life. “Don’t be impertinent, boy! You –”

The cupboard shook violently, as if rocked by an earthquake. “Listen to your aunt, boy!” Vernon’s voice boomed all around them. “Quiet, boy! I’ll teach you not to look at me that way, boy!”

Harry curled in on himself, flattening his hands over his ears to block out the sounds. Aunt Petunia’s shrieks joined in after a bit. Other shouts followed soon after. He tried to ignore them all. He imagined retreating far, far away, like he used to do to escape his fear and his anger and his misery, but it wasn’t working like it usually did.

“Potter. Potter! Harry!”

Harry gave a little start. That was Snape’s voice, and he sounded panicked. It snapped Harry back to attention, and he looked up to see the cupboard in disarray. Black tendrils were creeping through the slats in the door. They shifted in form – one second the tentacles of the Giant Squid, the next the tendrils of Devil’s Snare, the next an acromantula leg.

The walls had shifted to a pearlescent grey. Shadows shifted outside, like the vague shapes in a Foe Glass. All of them, silhouettes and smoky tentacles – were reaching for Snape, who had retreated as far from both Harry and the door as he could, which meant that he was huddled on the cot.

Seeing that he had finally grabbed Harry’s attention, Snape continued quickly but calmly, “Stop trying to Occlude. You are currently Occluding, so to Occlude further would be to drive this place deeper into your mind. That would be useful if you were being mentally assailed, but your source of stress is me, so you would just plunge us deeper and deeper, until you were too confused and I was too weak to return to the surface of your mind. Breathe in with me.” Harry obediently breathed in with Snape. “Breathe out.” He did. Snape repeated this until the cupboard returned to normal and the voices had faded to a murmur.

“Perhaps,” Snape ventured after a moment, “you should let me go, and we could continue this discussion out of your mind.” _Out of danger_ was implied.

Harry shook his head frantically. “No, no,” he protested. “I can’t.” Snape couldn’t hurt him when he was here. They could talk, but Snape couldn’t hurt him. If he did, Harry could hurt him back.

“Why not?” Snape bit out, obviously refraining from an angry outburst.

Harry didn’t reply. You couldn’t tell someone that you were afraid of them hurting you – either they got even more angry, or they realized how much power they truly had over you. Neither was a good option. The best strategy was to pretend like you weren’t scared of them at all.

Snape studied Harry in silence for a few long moments. As he did, the pinched look on his face smoothed out into something unreadable. Harry shifted uncomfortably under his scrutiny.

“Fine,” Snape acquiesced, to Harry’s surprise. He had expected more yelling and insults. Snape tried to settle himself more comfortably on the cot, but Harry knew from experience that there were no comfortable spots. “We can talk here.”

“Alright,” Harry replied cautiously.

There was an awkward silence. Harry shuffled his feet on the dirty floorboards.

“Occlumency,” Snape said suddenly, breaking the silence, “can be either defensive or offensive. Defensive Occlumency is the branch that I was attempting to teach you – it is recommended for beginners and those who do not possess the amount of painful memories or the correct disposition necessary for offensive Occlumency. You clear your mind, removing all memories from easy reach of the Legilimens. After this basic strategy is achieved, the Legilimens can attack the deeper mind. The Occlumens will instinctively retreat, creating a refuge. From this stronghold, other fortifications can be built, and eventually, the mind becomes an unassailable fortress. Are you following me so far?”

Harry gave Snape a sharp nod.

“However,” Snape continued, “in your case, defensive Occlumency would be impossible, or at least exceedingly difficult to implement, since you have already constructed the basis of an offensive system of defenses.”

“How did I do that?” Harry interjected. “I’ve never heard of Occlumency before this year.”

Snape studied him intently. “Let me guess. They would shout, your guardians, shout and scream and maybe even hit you, so you would sit here and send your mind far away. You would imagine you were in a peaceful room, and then you would expand outwards from that. You would imagine that outside of this room, your guardians would drop dead. Perhaps you imagined someone coming to rescue you, and they would open the door, and you and your rescuer would laugh in your previous guardians’ faces. You would imagine that your guardians would be hit and screamed at and be forced to take refuge themselves.”

Harry stared at him, unable to defend… the Dursleys? Himself? He didn’t know.

“Offensive Occlumency,” Snape explained softly, locking eyes with Harry, “is not formed from a calm mind and deep defenses. Instead, the Occlumens wields their own terrible memories against the invading Legilimens. It is born out of an impulse for retribution. You could not have possibly cleared your mind – your defenses are based on the accessibility of your memories.”

Harry looked away, unable to hold Snape’s gaze. “Which type do you practice?”

“Both.”

“Which one did you practice first?”

Snape smiled sardonically. “Which do you think?”

Harry huffed out a small laugh. Yeah, a technique that relied on spite and retribution sounded like it was right up Snape’s alley.

“But if I’m using offensive Occlumency, then why do I have this?” Harry asked, gesturing to the surrounding cupboard. Snape was actually explaining things fully, and he wasn’t going to squander this chance to get real answers. “I thought you said visualization was part of defensive Occlumency.”

“It is,” Snape replied. “But those who use offensive Occlumency generally have remnants of their attempts at defensive Occlumency scattered around their mind. I am positive that you’ve utilized this safe haven frequently, but I doubt that this… room,” Snape sneered at the word, “is still your conception of a refuge. Even now, you did not use it to defend yourself, but to attack me.”

Harry nodded slowly. It made sense, when he thought about his childhood. “Is this common?” he questioned. “Developing Occlumency skills unconsciously, I mean.”

“No,” Snape answered, with a pinched, bitter expression. “Spontaneous Occlumency points to childhood trauma, generally long-term child abuse.” He turned a piercing gaze on Harry. “How _do_ your relatives treat you, Potter?”

Harry let the cupboard go, booting Snape out as he did. He briefly felt the professor’s surprise as he whacked him out of the dissolving cupboard and back into his own mind.

He opened his eyes to the familiar sight of the Potions Master’s office. He was sprawled on the floor, and as he laboriously rose to his feet, he saw Snape picking himself up as well. It was strange seeing him without the serious injuries he had obtained in Harry’s mind. When the professor turned towards him, he braced himself for… something. Curses, hexes, a good old-fashioned slap.

But Snape just limped over to his desk and collapsed into his chair. “Dismissed, Potter,” he said. “We’ll resume next week.”

Harry knew he should just embrace his good fortune and leave, but… “That’s it?” he asked incredulously.

“What are you blathering on about, Potter?” Snape sniped tiredly, not even looking at Harry. He started shuffling through a pile of papers on his desk.

“I… attacked you,” Harry ventured. “That’s… this is….”

Snape’s grip tightened on the papers until they began to crinkle. “That was Occlumency, which is the express purpose of these sessions. I would be a poor teacher if I punished you for it.”

Harry wanted to reply with several inadvisable comments, like that Snape certainly hadn’t let being a poor teacher stop him in the past, but he held his tongue. Instead, he nodded briskly to Snape and collected his things, leaving before Snape changed his mind. Unlike all the sessions before, Snape didn’t throw out a harsh reminder to clear his mind before he went to sleep.

He wondered what the next session would bring.


	2. Torque

**Summary for the Chapter:**

> Torque - the change in the angular momentum of a system

Hermione pestered him to tell her how the session had gone. He had thrown out some pithy comment about how he was improving. Luckily, there were other matters to occupy their attention, like Umbridge and the DA, so she didn’t push for details. During the next week, Harry also had another dream about the long, dark hallway. It didn’t seem that his discovery of his foundation in offensive Occlumency helped in this regard.

The next week, he approached Snape’s office with a sinking sense of dread in his stomach. Snape had been his normal level of unpleasant in Potions classes during the week, but when they were alone… Harry was sure Snape would try to get him back for Harry’s vicious Occlumency attack.

But when he entered the office, Snape was seated at his desk, and the papers and vials had been cleared off to make room for a tea tray. There was a steaming teapot and two delicate china teacups, as well as a plate of biscuits. Harry stared at the setup incredulously.

“Well?” Snape snapped. “Don’t just stand there gawking, Potter. Sit down.”

Obediently, Harry sank into the chair in front of Snape’s desk.

Snape silently poured them both cups of tea and handed one to Harry. Harry didn’t take a sip until Snape did. He considered sniffing the tea for any potions, but he figured that any potion Snape would dose him with would be odorless, or at least above his skill level to detect.

They drank the tea in silence for a few moments before Snape spoke up. “I have regrettably been… basing these lessons on assumptions that have since been debunked,” he admitted, a bitter twist to his lips. “I would not have believed that Harry Potter had spontaneously developed a proficiency in offensive Occlumency if I had not felt it for myself.”

“Why?” Harry couldn’t help but ask sardonically. “Because of the amount of bad memories needed, or because of my disposition?”

Snape seemed surprised at Harry’s recall of the details of Occlumency. Harry had to fight down the surge of anger. If Snape hadn’t written him off after the first lecture of his first potions class, he would have seen that Harry had a knack for memorization – Ancient Runes was by far and away his best and favorite class, and most of the details in Harry’s potions essays came verbatim from Snape’s lectures.

“Both,” Snape said, startling Harry. He hadn’t expected this level of honesty from the professor. It was like they were back in the cupboard, but the threat of Harry’s aggressive memories wasn’t hanging over Snape’s head now. Harry couldn’t think of why he could be acting like this. “As well as the precipitating circumstances. Your home life,” he clarified at Harry’s confused look.

Harry shrunk back into his seat. Snape wouldn’t bring this up again, would he?

Snape waved his hand negligently. “I won’t question you about that now. It wouldn’t be admissible in court in any case.”

“What?” Harry asked, confused at the turn this conversation had taken. “Why not?”

“Because I dosed the tea with Veritaserum,” Snape told him bluntly. “Both of us are under its influence.”

“What?” Harry cried, leaping out of his chair. “Why would you do that?”

“Your Occlumency is a blunt-force tool, only suitable to defend against direct Legilimency attacks,” Snape informed him. “It cannot assist you with your dreams or against subtler methods of manipulation, like truth potions. Thus, today we will be attempting to refine your control.” He took a deep breath as the Veritaserum-forced answer came to an end. “Mr. Potter, sit down.”

Harry sat down. “You… didn’t have to dose yourself,” he ventured.

“Would you have returned to these lessons if I had dosed only you?”

“Yes,” Harry replied, the truth punched out of him. He tried to stop his mouth, but the potion was stronger. “There are worse things that you could have done to me. That you have done to me.”

Snape stared at him, face impassive. “We will be restricting our questions to innocent topics only,” he said, bluntly changing the subject. “I will require no oath, but if you escalate the seriousness of the questions, I will do so in return. Your goal is to twist the truth enough that I could assume a different answer than the truthful one. I do not expect you to be able to lie at this stage of your training. Do you understand?”

Yes, Harry tried to say, but instead, he blurted out, “Not really.”

Snape smirked. “You will learn, I assure you. If you are confused on how to answer a question with a misleading truth, you may ask me a question as a demonstration.”

 _I really don’t need any help with that_ , Harry thought. He didn’t want to explain that to Snape though, if the man would even believe him in the first place. Snape considered Harry the personification of Gryffindor bluntness and recklessness – Harry had found that blind conviction from an otherwise perceptive man to be aggravating, but useful.

“What’s your favorite color?” he asked instead.

Snape shot him a look that told Harry how asinine the professor had found his question. “It’s certainly not black,” he drawled. “Closer to green, I’d say.” He smirked at Harry. “Well, Potter? What is the truth?”

 _Green_ , Harry wanted to say, because that would be the expected, stupid answer. “Gray,” he replied, the word ripped out of him.

Snape raised his eyebrows incredulously. “Better than expected, Potter. Care to elaborate?”

Well, Snape was trying to mislead him, so he had obviously shifted things around so that his definition of “closer to” was different than would be expected. But he wasn’t lying outright, so Harry knew it truly wasn’t black. Gray was very close to black in most people’s minds, so leading with black and then contrasting it with a different color meant that Snape had wanted to drive him away from black. Thus, gray was a fair guess. But Snape had only asked him if he wanted to go into detail, so – “No,” Harry answered.

Snape looked annoyed, so they were back in familiar territory. “What was your reasoning for why my favorite color was gray, Potter?”

Now would be a great time to halt the babble that wanted to burst out of Harry’s lips. “Well, your robes –” _are gray_ , Harry tried to say, but his mouth blurted out, “are black, so it might make sense to lead with mentioning black –” _Okay,_ Harry realized, _I can drive the direction of the truth, as long as I never lie. I need some time to think._ He didn’t think the potion or Snape would give him that time, so he tentatively sunk into his cupboard. Surrounded by the dusty walls, he dispassionately observed the train of thought, nudging words into place to influence the flow of his rambling. He wasn’t able to dissemble, not really, and when he emerged from the cupboard, he found Snape staring at him contemplatively, with a hint of a smirk at the corners of his mouth.

“Defensive Occlumency is not likely to serve you well here,” Snape told him. “You retreated to your… room, did you not?”

“I did,” Harry replied, even though he felt the question was largely rhetorical. The Veritaserum didn’t agree with him on that, it seemed.

Snape nodded, almost agreeably. “You have discerned the correct theory –” and he only sounded a little surprised this time, Harry noted sardonically. “But that method requires you to have constructed more profound defenses than a single, although well-fortified, refuge. You achieved the required distance of mind, but without more advanced techniques, you will only be able to ramble about your attempts to logically assess my… favorite color.”

“Was I right?” Harry asked cheekily. He wondered how far he could push Snape until, like in the cupboard, the man abandoned this pretense of civility. Snape hated Harry, and that was a constant in his life. It had been easier to deal with than this new, unpredictable Snape.

“Yes,” Snape replied, a scowl on his face. “And I would appreciate you not to waste our time with such irrelevant questions, Potter. Let’s try once again.” Oh no, Harry wasn’t ready. He’d been analyzing Snape instead of figuring out how to use offensive Occlumency to block the Veritaserum. Well, it was too late now. Snape smirked at Harry as if he knew the direction his thoughts had taken. “What is your favorite class?”

Harry dove into his mind, down past the cupboard, into the depths of the tangle of his memories. The world slowed to a crawl. “Okay,” Harry said to himself and to his writhing memories. “Offensive Occlumency. How do we use it to twist the truth?”

What was offensive Occlumency, really? Harry had to start there. Snape had told him it was about retribution and using memories as weapons instead of simply protecting them. So, logically, Harry would have to martial some sort of anger or vengeance on the idea of telling the truth? No, that was too vague.

Ah, Harry realized. No, he would have to attack the root of the problem – the Veritaserum itself. He would have to rally his anger and terror at his own helplessness and lack of control and wield that against the potion.

So he dug into the fire of his emotions – first he took the humiliation of helplessness, the shame at his thoughts being on display for a man who hated him, and the rage that simmered under it all. Next he reached for the fear of honesty, the beatings and the days without food that he had narrowly avoided with a well-crafted lie. He imagined the horrors that would have resulted from complete honesty. These would be the core of his weapon.

He bound them together with resentment. Dudley lying, over and over, making Harry bear the weight of Dudley’s crimes. Malfoy turning Snape’s ire on him with sugared words. They could get away with lying, he thought. They were praised for it. Why not him? Why couldn’t Harry lie?

With that thought, he felt a foreign presence in his mind pulse softly. It was everywhere, he realized, an amorphous smoke that wound its way through his thoughts. For a moment, he was frustrated. There was no solid core to aim at, only a formless gas. 

He had a few frustrated moments before he realized that this was his mind – he could scoop it up or capture it like he had with Snape. He imagined a tiny cupboard and then stuffed the Veritaserum into it. It placidly accepted its confinement, only a few tendrils trying half-hearted to escape. Harry contemplated the trapped Veritaserum for a moment and then _plunged_ his memory-weapon into it.

Suddenly, he could feel the difference, like the fog lifting in the morning – a haziness that he had barely noticed until now being chased away by the warmth of the sun. He knew with utmost certainty that he could lie now. The potion’s influence was gone.

“Potions,” he told Snape. He savored the subtle widening of the man’s eyes for a moment, basked in the victory of his surprise.

And then the Veritaserum broke loose.

It lunged out of the cupboard, shattering it with a sound like that of a gong. It reverberated in Harry’s head. Its smoky tendrils lashed at him. All its former placidity was gone. He tried to fight back, but his skull was ringing with the echoes of the cupboard. He tried to escape, but he couldn’t run.

Distantly, he could hear himself speak. “Ancient Runes,” he babbled to Snape. “I’m good at it – I might want to be a wardmaster, actually, if I manage to survive Hogwarts.” _Shut up_ , he thought to himself viciously. _Snape doesn’t need to know this._ But his head was still echoing, and the Veritaserum was still ripping at him. The truth tumbled out of his mouth, unstoppable.

“Potions might have been my favorite if things were different.” _No, he doesn’t need to know this!_ Harry tried to clamp a hand over his mouth, but he could only twitch his hand across Snape’s desk.

“I was really excited about it, you know? That first day. But then you hated me. I couldn’t just behave and keep my head down – that never works with people who hate you for who you are.” _Please, stop,_ he thought at himself, at the Veritaserum, at his stupid, babbling mouth.

“Potter,” he heard Snape say. “Potter, there’s a reason I told you to use misdirection. Veritaserum has a harsh kickback for lies.”

“Aunt Petunia hated me for being good at cooking. She shouldn’t have, because she told me to do it, and she punished me when I was bad at it.” _Shut up, shut up._ “But she loved cooking and she hated me, and she couldn’t reconcile that. It made her hate me more.”

“Potter, retreat. Go into your refuge.”

 _The Veritaserum broke it,_ he wanted to say. “So I couldn’t try to be good at Potions. You had a wand. And I think you’d fit into my cupboard. I had nowhere to run from you, so I had to stand my ground.”

“Potter.” Snape was in front of him now, a long-fingered hand grasping his chin, tilting it up so that Snape could stare into his eyes. “Do I have to interfere?”

The question didn’t even register. The truth had Harry firmly in its grip, and he couldn’t escape. “I think I would like Potions. It’s logical and complex. But if I turned out to be good at it, how much more would you hate me?”

“Fuck,” Snape muttered. “Well, that answers that. _Legilimens._ ”

He could feel Snape entering his mind, but the Veritaserum still had him in its grasp. He struggled against it, but once again, it was futile. Suddenly, he was ripped from it, and he tumbled down, down….

And appeared in his cupboard with Snape. “What?” Harry breathed, touching the grime-streaked walls. “But the Veritaserum shattered this.”

“What?” Snape snapped. “Shattered your refuge? What the hell did you do, Potter?”

Harry shrugged. “I made a memory-weapon and then I collected all the Veritaserum in my cupboard. And then I… speared it. It worked for a moment. But then the Veritaserum shattered my cupboard and escaped.”

Snape sighed, sinking down onto Harry’s cot. “You just tried to use an advanced technique without knowing any of the basics,” he informed Harry tiredly. His usual ire was nowhere to be seen. Instead he just looked… exhausted. “That would have worked with a lesser truth potion, and it would have worked if you had chosen to misdirect instead of lying. Veritaserum was created to prevent what you just tried to do, however. Successfully telling a lie while dosed with Veritaserum will cause a reaction in the potion, and it will force you to tell the whole truth, especially things that you would rather keep hidden.”

Harry felt a bit like crying. “I didn't know that,” he told Snape, uselessly, stupidly.

Snape looked at Harry like he never had before, like he was actually seeing Harry and not his own ghosts. “No, I suppose there was no reason that you would have. We don't cover Veritaserum until NEWT-level potions.”

Harry dropped onto the floor and hugged his knees to his chest. “What'm I supposed to do, then?”

“I'll give you a book,” Snape replied, his voice still utterly devoid of malice. “You like Ancient Runes - how far ahead of the curriculum are you?”

Harry stared at him in shock, mute. Snape… assuming that he was ahead in a class? Not “skating by on his fame, lazy like his father”?

Snape snorted. “Don't give me that look, Potter. If Ancient Runes is your favorite class, you've certainly found it to be unacceptably slow.”

Well, Snape wasn't wrong. “I'm fluent in Elder and Younger Futhark and I'm picking up Phoenician and Ogham.”

Snape's eyebrows rose but he didn't comment. “The best book is in Younger Futhark. You can borrow the original since you don't require a translation.”

“Is there one?” Harry wanted to know.

Snape grimaced. “Outlawed, but there's a loophole in the law if a translation and not the original is listed as banned.”

Harry nodded. “Yeah, the original's fine.” He didn't ask why Snape hadn't mentioned the book before.

They sat in silence for a long moment. Harry could still feel the Veritaserum raging, but he and Snape were far enough removed that he was blissfully unaware of the uncomfortable truths that he was no doubt spilling to his teacher in the real world.

“I… There are…” For the first time since Harry had met him, Snape was stumbling over his words. “If you would like additional books, I could also recommend some supplementary potions books.”

Harry sighed and dropped his head into his hands. “Let’s just pretend it didn’t happen, okay?”

“What?” Snape snapped.

“That - all that stuff I said. It’s fine, sir. You don’t - You don’t have to pity me, okay?” He shrugged. “I do well enough to fix most of the potions when Malfoy messes with them, so I’m sure I’ll do decent on my Potions OWL.”

Snape’s eyes narrowed. “Mr. Malfoy sabotages you?”

Harry snorted. “Please, sir, like you don’t notice. You can tell that Hermione took her potion off the heat a half-minute too early - you can certainly tell when Malfoy tosses a couple frog livers in mine.”

Harry cringed automatically, sure that Snape was going to be angry about the sass. But Snape was silent for a long moment. He studied Harry critically. Harry kept his gaze on the floor and concentrated on the lashes of Veritaserum on the cupboard walls.

“What additional books did you read?” he asked Harry finally.

Harry shrugged. “I don’t remember exactly. The most useful was the Compleat Compendium of Reactants and their Interactions, though.”

Snape’s eyebrows rose. “I found the Compendium rather dry,” he remarked mildly.

Harry huffed out a laugh. “Yeah, me too,” he admitted. “But the table is easy to remember and super helpful.”

“Easy to remember?” Snape echoed with a touch of incredulity.

Harry sighed. Hermione had the same reaction when he’d told her that he’d memorized the 25 page table. “It’s just memorization. Even a stupid kid like me can do it.”

Snape simply hummed, his intense gaze fixed on Harry. “What would you do if you were at the third step of the Wiggenweld potion and Mr. Malfoy added a billywig stinger?” he asked, apropos of nothing.

It took a moment for Harry to remember the potion and the steps. He catalogued the current ingredients that would be in the potion - salamander blood, flobberworm mucus, wormwood. “Billywig stingers are primarily caustic, air-aligned, volatile, moon-independent, and sun-linked,” Harry worked through it thoughtfully. “Salamander blood is also volatile but is fire-aligned, so I’d have to first neutralize the explosion. Salamander blood is alkaline, so if I add another alkaline ingredient that is earth-aligned and stable, I should be able to buy myself some time.” 

He thought for a second before the proper solution jumped out at him. “Willow bark, cut into long strips. Earth and water-aligned, which would be a problem except that the whole potion shifts elemental alignment at step 13. I’d just have to modulate the addition of frog spawn and add some sort of stabilizer.” He snapped his fingers decisively. “More flobberworm mucus.”

Harry looked to Snape to see if he had answered the question correctly and found the man staring at him strangely. “Sir?” he ventured.

“That’s not memorization,” Snape replied with that weird expression still on his face.

“Yes it is,” Harry disagreed, puzzled. “Caustic-air-volatile combined with -”

“No,” Snape interrupted. “I meant that your answer was not merely memorization. You understand the ingredients and their interactions.”

“Because I memorized them?” Harry didn’t understand what Snape was trying to get at here.

“Do you purposefully turn in subpar essays?”

Harry just shrugged, confused and wary about this line of questioning.

“Answer the question, Mr. Potter,” Snape demanded.

“I’ve been answering an awful lot of questions,” Harry retorted back. “Maybe it’s your turn.”

They both froze. Harry bit his lip and cursed himself for a fool. He’d let his guard down around this strange Snape, but he was intimately familiar with how adults who didn’t like him reacted to his “cheek”.

“Fine,” Snape replied after a long moment, startling Harry. “What do you want to know?”

Stunned that Snape was even asking him that - him, Harry Potter, who Snape despised - he threw out the first question that was on his mind. “Why are you asking me about Potions?”

Snape grimaced. “I had assumed that the consistent imperfections in your potions throughout the years were to be attributed to a lack of care or a lack of dedication. I was aware of the rare sabotage, but you have apparently been successfully correcting almost all of your sabotaged potions so that they appear as a slightly subpar version of the assigned potion. Your essays did nothing to disabuse me of my initial assumption, as they seem to be the haphazard work of a careless student. But you obviously have a deeper understanding of this subject than I expected.”

Harry hadn’t expected Snape to answer, much less to answer in such depth. He struggled for an appropriate reply.

Snape smirked at Harry’s gobsmacked expression. “Will you answer my question now, Mr. Potter? Why the poor essays?”

Harry huffed out a frustrated breath. “Because they take a lot of time to write and I don’t do it very well.” He wiggled his crooked fingers at Snape in demonstration. “Since I don’t do well in Potions either way, it makes more sense for me to devote the time to Transfiguration or Charms.”

Snape stared at Harry’s fingers. “Do they hurt or ache when you write?”

“Don’t I get another question?” Harry deflected. This was getting uncomfortably close to discussing things that he’d rather not.

Snape clicked his tongue impatiently. “What do you want to know?”

Harry was more prepared this time. “Why do you care? I mean, about how much I actually understand Potions or Runes or whatever?”

Snape’s expression was strangely blank when he replied, “I don’t like being purposefully misled.”

That was all he said, and Harry knew the man wouldn’t elaborate further. “Yes,” he answered in return, not making Snape ask the question again. “I was okay writing with a pen, but the way that you’re supposed to hold a quill makes my fingers ache.” If Snape could get away with the bare bones of an answer, so could Harry.

Snape accepted Harry’s explanation with a nod. “If you re-break them and use the proper potions, you could almost certainly regain full functionality.”

Harry perked up at this. “Really?”

Snape nodded. “As long as the injuries are less than ten years old, the potions regime has a 95% success rate.”

“Oh.” Harry let his head fall heavily onto his knees. “That won’t help then.”

Snape froze. “You broke them when you were five?” he asked with a thin veneer of calm.

Harry snorted. “Four.”

“Four,” Snape repeated, deadly. “And how did you break them?”

“Not your turn, Professor,” Harry said, and then fell silent.

Snape waited for Harry to ask a question, but when it became apparent that Harry would remain stubbornly silent, he returned his searching gaze to the cupboard. Harry wasn’t sure what Snape would see, but there were too many of his secrets in here for him to be comfortable with Snape’s scrutiny. The Veritaserum was beating at the cupboard with less frequency now and its lashes were weaker and weaker.

“Can we leave now?” Harry asked finally.

Snape tilted his head to the side, listening to the Veritaserum’s struggles. “I suppose so, but keep your mouth shut until I administer the antidote. He abruptly vanished from the cupboard, leaving Harry to follow behind.

When Harry regained a sense of the outside world, his mouth was mercifully closed and Snape was rummaging around in a box, the clinking of the vials cluing Harry into its contents. Finally, Snape pulled out a tiny gold-stoppered vial.

“More volatile than even Veritaserum,” he muttered to himself. “Open your mouth, Potter.”

Harry obediently opened his mouth and allowed Snape to pour all the contents onto his tongue. Immediately, he could feel the aggressive fog in his mind clearing. “Thank Merlin,” he sighed, massaging his jaw. “Fuck.”

“Language, Mr. Potter,” Snape reprimanded him lazily, but he wasn’t even looking at Harry, more engrossed with the box of potions. “What did we learn today?”

There was a blessed lack of an urge to reply. “Don’t get dosed with Veritaserum,” Harry said, of his own volition.

“I’m sure,” Snape returned blandly. “And if you are?”

“Don’t stab it and then lie?”

Snape’s mouth curled into something between a grimace and a smirk. “More or less. Get out of here, Potter.”

“Yes, sir,” Harry said, and very pointedly left the room at a walk. He didn’t burst into a run until he was clear of the dungeons.

**Notes for the Chapter:**

> Wow another chapter! Thanks to astahfrith for betaing and cheerleading! You get another chapter right now because I just finished chapter 6. The update schedule will be whenever I finish a chap or a month after I posted the last chap, whichever comes first.
> 
> Thank you to all my early commenters and bookmarkers and kudosers! I love you all.


	3. Chain Reaction

**Summary for the Chapter:**

> Chain reaction - A sequence of reactions in which a reactive product or byproduct causes additional similar reactions to take place.

“Pleasant dreams potion,” said Snape, rapping sharply on the blackboard with his wand. Familiar spindly writing spilled across the board. “Also marketed as Beddy-bye potion. Five points from Gryffindor for laughing in class, Ms. Brown. Can anyone tell me about the effects of this potion? Yes, Mr. Malfoy.”

“It encourages pleasant dreams in children, Professor,” Malfoy answered smugly.

“Five points to Slytherin. Can someone else tell me the restrictions on this potion’s use? Mr. Malfoy alluded to the answer already. How about you, Weasley?”

“U-uh,” Ron stuttered. “Only children can use it?”

“Incorrect, Weasley. Did you even read the chapter?” Malfoy and his goons snickered. Harry imagined punching them in their smug, poncy faces. “Let’s try again. Ms. Patil?”

“Umm, it can’t encourage pleasant dreams if the source of the dream is rooted in deep fears? Like if someone is dreaming about a murder they witnessed, it wouldn’t affect those dreams?”

“More or less, yes.” Snape replied. Harry noticed that, like usual, Gryffindor didn’t receive any points for correct answers. “Age is not necessarily a factor of success for this potion. An adult with an absence of traumatic experiences would likely be affected by the Pleasant Dreams potion, while a child with major trauma would likely be unaffected. What potion is used in cases when Pleasant Dreams would be ineffective? Mr. Zabini.”

“Dreamless Sleep, Professor.”

“Correct, Mr. Zabini. Five points to Slytherin. And why is using Pleasant Dreams preferable to administering Dreamless Sleep? Anyone? Fine. Granger."

"Dreamless Sleep contains poppy extract," Hermione answered. She hadn't raised her hand - Snape had banned her from doing so in his class sometime around second year. He'd snarled that he would "call on you when I feel it necessary, Ms. Granger," which really meant that he'd single her out when no one else would raise their hands. She'd gotten all his questions right since first year, but he'd never given her a single point.

"Poppy has addictive properties, and combined with the soporific qualities of valerian -"

"Get to the point, Ms. Granger," Snape interrupted.

"Pleasant Dreams isn't addictive, while Dreamless Sleep is one of the most commonly abused potions," Hermione finished in a rush.

"And what is the key difference between these two potions? Potter."

Harry hadn't raised his hand either, but that had never stopped Snape. 

Snape hadn’t covered this in class, and it hadn't been in the assigned reading. That wasn't a surprise either.

Harry considered the ingredients of both potions. There was the obvious poppy difference that Hermione had pointed out. But there was also the fact that moonstone was used in the base of Dreamless Sleep, which made it a strongly moon-linked brew. The poppy and valerian combination also provided a strong, stable tenor to the potion.

On the other hand, Pleasant Dreams had no moonstone - in fact, there were no strong sun- or moon-linked ingredients in the brew at all. This neutrality (and the slight water nature of the potion) was essential for the correct action of the lotus shavings. Like most aquatic plants, lotus' effects would change drastically if there was a strong preference towards one celestial body. 

But valerian required a strong moon-linkage to act at full strength as a sleeping agent. Thus, the neutrality of Pleasant Dreams undermined the soporific effects of valerian, and this is why it didn't work in some cases.

Pleased that he had worked it out, Harry leaned back in his seat with a small smile. "No idea," he told Snape blithely.

Snape's mouth tightened with something that wasn't his usual irritation. If Harry didn't know better, he'd call it disappointment.

With a dramatic billowing of robes, Snape whirled to pace back to the front of the classroom. "Retrieve any ingredients you must from the storeroom," he barked. "This potion will take the whole double period to brew - what is so important, Ms. Granger?"

"Sir," Hermione replied, lowering her raised hand. "What's the answer to the question you asked Harry?"

Snape's mouth twisted into a scowl. "Moonstone," he snapped.

"Well, that was clear," Ron muttered to Harry as they set up their stations. The clanging of cauldrons masked their conversation.

"I'll explain it to you later," Harry promised. He left his station under the watchful eyes of Ron and Hermione. Malfoy wouldn't try anything with witnesses.

Harry grabbed everything that he suspected might be useful if Malfoy messed with his potion. He'd already worked out the solutions to some of the common sabotages that Malfoy could use.

He was eight steps in when it finally happened. Something plopped into the center of his cauldron, punctuated by Malfoy's snigger. Something that looked suspiciously like fluxweed.

Harry froze. The liquid in his cauldron began to shift from a pale pink to a deep, dark blue. Shit. He hadn't planned for this.

Fluxweed was an intensely moon-linked ingredient - so much so that the phase of the moon when it was harvested had drastic effects on its potency. Harry had expected Malfoy to go for the low-hanging fruit - there was a dilution of glumbumble treacle on step four that would react explosively with anything sun-linked. That actually would have been a relatively easy fix - Harry had ingots of iron on hand, which could sequester the glumbumble until Harry was ready to re-integrate it.

Well, Harry said “easy fix” - the technique was actually somewhat difficult. It only worked for him about half the time. Still, Harry had prepared for that. He hadn’t prepared for contamination with a moon-linked ingredient. Harry had to give Malfoy credit - he had to have understood the potion deeply to pick such a subtle but effective sabotage.

The valerian was already added and was reacting with the fluxweed, hence the change to the deep blue color. If Harry added the lotus root in this condition, the drinker would enter a deep catatonic state, where they would experience any dreams vividly, to the point where they would believe that they were real events. Additionally, since fluxweed was often used in potions that required a sense of change or flexibility, the dreams would likely be unusually surreal. All in all, not a successful potion.

While Harry was pondering his next step (introduce some euphoric ingredients? Play off the flexibility of fluxweed and simply mitigate the strength of the valerian?), Snape swept by his station in a flurry of robes. Harry was stunned to realize that he’d surreptitiously left a handful of morning glories on Harry’s desk.

Was Harry supposed to fix his potion with _these_? He didn’t see how. Morning glories were extremely sun-linked, which, while possibly able to modulate the moon-linked nature of the brew, would react violently with the glumbumble treacle. And even if one ignored the treacle, changing the celestial linkage of a brew would depend on the phase of the moon it was currently linked to and the present position of the sun, the moon, and even the stars. 

Harry just didn’t understand… wait.

A possible plan unfolded as he stared at the morning glories in front of him. It was insane, tricky - he had no idea if it was what Snape had intended him to do when he had dropped the flowers on his desk. But it had a non-zero chance of working, so it was better than any other options. 

He leaned forward over his desk. “Neville,” he said in an undertone, “can I have -”

“Yeah, sure, Harry,” Neville interrupted, nudging his book bag back with his heel. Harry noticed it was already opened and in a good position for Harry to reach into it. It was almost like they’d done this before, Harry thought sardonically.

Harry extracted a nondescript wooden box from Neville’s bag. He unlatched it and flipped it open to reveal an endless series of boxes filled to the brim with magical plants. Ever since the beginning of third year, Harry didn’t use plant ingredients for his potion corrections that hadn’t been grown, harvested, and dried by Neville. The ones in the potions storeroom were of varying quality - Snape didn’t have the time or resources to buy the best for Hogwarts students, nor was that level of quality required in Hogwarts-taught brews. But Neville’s ingredients were always of perfect quality, free of contaminants and imperfections - and it was this level of perfection that Harry needed when working with the volatile potions that Malfoy’s sabotages produced.

He pulled out several sprigs of dried asphodel, and after a moment of thought, grabbed a few alihotsy leaves and a bundle of hellebore.

“Hermione,” he hissed.

“List,” she demanded, not even looking up from her chopping.

“Newt eyes and, uhh… shrake spines.”

“Shrake spines? Are you sure?”

“Hermione, this potion is going to be unsalvageable in a minute.”

She nodded, and briskly wove her way to the potions cupboard. Harry chopped the asphodel while he waited for her and collected the minced asphodel into a cup. The morning glories were similarly minced and collected in a separate cup. He’d have to be fast about this.

Hermione returned and surreptitiously placed the requested ingredients on his bench.

Harry took a deep breath to center himself. _Calm and clear_ , he thought to himself, and felt the anxiety quiet down and draw back into his bones. His hands couldn’t shake during this. _Calm and clear_.

“Shields,” he ordered quietly. Neville, Hermione, and Ron threw up transparent shields without a beat. Ron’s shield even cleanly bisected his and Harry’s bench, covering all of Ron’s ingredients from potential harm.

It was time. One, two, and Harry spread the minced asphodel on the deep blue surface of the potion. It began to bubble threateningly as the asphodel reacted negatively with the fluxweed. Three, four, and Harry threw in the morning glories.

The potion _boiled_. If it exploded, the classroom would be all but leveled. Harry was essentially building two opposed explosive reactions, and they would feed off of each other to produce a brief, devastating eruption.

Harry waited for half a second. He had to let this go on _just_ long enough without it turning into a catastrophe.

Just as the potion boiled over the rim of the cauldron, Harry threw the iron ingots into the brew. The few splashes of the potion that had escaped the cauldron hissed and spat as they hit the floor, eating pits into the stone. But the majority of the potion calmed, settling once again into a still expanse of liquid. However, now the color was a strange greenish yellow instead of the former dark blue.

Harry glanced up to see if anyone in the class had registered their potential doom, and found Snape staring at him, his wand clutched in a white-knucked hand.

Harry was too tired to try to decipher the emotions in that dark, heavy gaze. He turned back to his potion.

From the looks of it, he’d been mostly successful with his main goal - he’d burnt off the fluxweed. He hadn’t wanted to try to neutralize the moon-linked nature of the fluxweed, especially since he would have been trying to bring it back to true neutrality - that would take almost impossible astronomical calculations. So instead, he had made it interact explosively with the asphodel, and then introduced an even more volatile reaction - morning glories with glumbumble treacle. The glory/treacle reaction was powerful enough to essentially burn away the weaker reaction. So Harry had eliminated the fluxweed, and now he just had to deal with the glumbumble treacle’s reaction to the sun-linked ingredient.

The iron ingots had been necessary to sequester the glumbumble treacle away from the rest of the potion. With an ingredient sequestered, it wouldn’t be able to react with the rest of the potion - it would be held in a sort of stasis away from the rest of the brew. Sequestering was a tricky technique, and Harry wasn’t sure he could pull it off in this case. Still, he was going to try. If nothing else, it gave him a little time to plan his next moves.

Over the next hour, Harry made a strongly water-aligned brew (with oily and alkaline characteristics) from the newt eyes and the shrake spines, and with that and essence of hellebore, coaxed the morning glories out of solution and into a vapor. The potion now smelled strongly of morning glories and Harry knew that it would taste like it as well. But at least the morning glories were in a gaseous state, and out of the liquid phase. A squeeze of alihotsy leaves separated the glumbumble treacle from the iron. Harry stirred carefully through this phase, as it was the second most delicate, just after the paired explosions. This was often where sequestration went wrong - a too-fast stir or a break in the rhythm could either knock the sequestered substances out of the iron too quickly or lock it in there, never to be recovered. Neither was a good result.

Somehow, Harry managed to successfully reintegrate the glumbumble treacle. He resisted the urge to pump his fist in the air. Now he just had to complete the potion and also neutralize the remaining bit of hellebore (while taking into account the new oily, alkaline nature of the potion) but that was trivial compared to the rest of the correction.

By the time Harry came out of his potion-trance, he had a passable Pleasant Dreams potion, and he was alone in the Potions classroom with Snape. That in itself was weird - usually Snape yelled at Harry to get out when he went overtime and vanished his partially completed potion. Or Neville and Hermione pulled him out of the classroom before Snape could do the honors. Harry wondered why they hadn’t this time. Had Snape told them not to?

Snape was staring at him again. He could feel the same dark, heavy gaze on the back of his neck as he bottled his potion.

He brought it up to the front desk and held it out to the other man. Snape didn’t take it from him, still too busy staring at him. Harry finally set it down on the desk with an awkward huff.

“You knew the answer to my question at the beginning of class.” It wasn’t a question. 

Harry shrugged in answer. He didn’t know what Snape was getting at.

The professor leaned forward in his seat intently. “There is no possible way that you corrected that brew, with _morning glories_ of all things, without intimately knowing every property of the ingredients in both Pleasant Dreams and Dreamless Sleep.”

Harry wrinkled his brow in confusion. “What do you mean, ‘morning glories of all things’? You gave them to me.”

Snape shrugged, a smirk playing about his mouth. “I picked them out of my stores randomly. I had no idea what I would place on your bench.”

Harry blinked, trying to process Snape’s words. “What? Why would you do that? There’s no way you just picked the one thing -”

“One thing?” Snape interrupted. “No, of course not. Think, Potter. What would you have done if, say, I had handed you horklump juice?”

_Horklump juice_ , Harry thought quickly, automatically. _Earth-aligned, stable, would combine with the valerian root and the fluxweed to produce a stable triad center, which would remove the moon influence, but I’d have to add another soporific agent, and I’d have to be careful with that potentially volatile horklump-fluxweed pair -_

“Okay,” Harry said. “Not just one thing. I see your point.”

“You didn’t answer the question, Potter,” snapped Snape. “Not this one, nor the one at the beginning of class. It does not, in fact, count as an answer if you figure out the correct solution in your head, but don’t bother to verbalize it. Revolutionary, I know.”

Harry glared at Snape, but figured it wasn’t worth the fight if Snape was so insistent to hear his thoughts about the questions. Generally Snape wasn’t interested in anything Harry had to say, so Harry had thought he was doing the man a favor. Apparently Snape didn’t agree.

So Harry explained the influence of moonstone in Dreamless Sleep and his potential process for correcting Pleasant Dreams with horklump juice. Snape didn’t interrupt him for the entire duration of his answer.

After he was finished, Snape nodded and leaned back in his chair. “Correct on all counts, Potter.” Somehow, he didn’t even say it like the compliment pained him, which was a first in Harry’s experience. “However, I believe you are laboring under quite a few misapprehensions. First and foremost, what you’re doing, this correction of Mr. Malfoy’s sabotages,” he waved his hand at Harry’s salvaged Pleasant Dreams potion, “is not an expected skill in OWL-level potions. In fact, this exercise - forcing a student to correct the addition of an incorrect ingredient with the addition of another, random component - is something expected of journeymen seeking their Potions Mastery. I have perhaps one NEWT-level student that could have done what you just did, but even then I doubt she would have arrived at the idea of two opposed, differentially volatile reactions to burn off the fluxweed. After five years of salvaging your potions, I gather that you, and perhaps even Mr. Weasley, Mr. Longbottom, and Ms. Granger, assume that this is a standard skill. It is not.”

Harry shrugged. “Okay, sure, but after five years, anyone would be good at it. I told you - I can memorize stuff. It doesn’t mean that I have any actual skill in Potions.”

Snape’s eyebrows rose and he fixed Harry with an incredulous stare. “What do you think ‘skill in Potions’ is then?”

“Producing a perfect potion?”

“If you can correct a potion, you could produce it perfectly given a safe environment. Correcting potions is a significantly more advanced skill."

"Okay, then, I couldn't create a potion. A new one, I mean."

"Fine," Snape replied. “If we use that as a baseline, then all my students are failing. You do realize that publishing a useful modification to an existing potion - just a single useful modification - is the criteria to move from apprentice to journeyman in a Potions Mastery? Are you going to tell me that you’ve never accomplished that? Never written a handy shortcut in the margins of a textbook?”

Harry couldn’t deny it, but he also couldn’t understand why Snape wanted him to _admit_ to it. “Why are you so insistent that I’m good at Potions?” Harry finally demanded, confused and desperate.

“Why are you so insistent that you’re _not_?”

The question hung between them in the silence that fell.

"If this is about Petunia," Snape began.

"It's not," Harry cut him off. "It's not. Just… forget about that shit I said, okay? Maybe that's how I thought about it first year, but not anymore. It's better. I'm better." He paused. "I just _can't_ be good at Potions, okay? I mean, you've been saying it for years. I'm skating along on my fame and I can't tell a pufferfish from a pomegranate.” Harry quoted Snape from earlier this year, when they were attempting to brew a Strengthening Solution.

Snape’s mouth drew into a narrow line. “I was obviously… mistaken,” he bit out.

Harry didn’t know how to respond to this. This situation - his Potions professor offering him the closest thing to an apology that he’d ever heard from the man - was nothing he could have expected or planned for. 

“Tell me, Mr. Potter," Snape continued after a moment, “do you plan to continue with Potions after Hogwarts?”

Harry couldn’t help himself. He snorted. Snape looked surprised, then furious. He opened his mouth to deliver a no-doubt scathing insult, but Harry held up a hand to stop him. Surprisingly, Snape actually backed down a little, although his rage was still evident in the lines of his body.

“I doubt there’s going to be an “after-Hogwarts” for me, Professor.”

Snape seemed shocked out of his anger. “What do you mean, Potter?”

Harry shrugged. “Voldemort’s back, Professor, and he wants me dead. I’d be very surprised if I make it to my 18th birthday.”

Snape paused for a long, heavy moment, his eyes once again fixed on Harry. Harry had a strange sense that Snape wasn’t really seeing him. He seemed to be looking right through Harry. 

Snape suddenly stood up, his chair scraping against the stone floor. “Dismissed, Potter,” he snapped, and before Harry could react, he had whirled into his office and slammed the door behind him.

Confused, and feeling off-kilter, Harry collected his various potion-making paraphernalia and headed off to dinner. He was certain that Hermione, Neville, and Ron would have questions about him staying late, but for the life of him, Harry didn’t know what he would tell them. He couldn’t understand what had just happened, or more importantly, what it all _meant_.

And it was only later, when he was lying in bed, staring up sleeplessly at the darkness above him, that he realized that Snape had referred to his aunt as "Petunia" - not "your aunt" or "your guardian". He'd referred to her almost familiarly. But how would Snape know his Muggle aunt?

**Notes for the Chapter:**

> It has been a week, so it's time for another chapter of Inertia!
> 
> Thanks as always to astahfrith for beta'ing!
> 
> Thank you all for reading and for your kind comments. I'm really excited for the direction this is going, and I hope you are too. this chapter was just a thin excuse for potions worldbuilding (this whole fic is just a thin excuse for potions worldbuilding). i'd love to hear your thoughts about it, so comment or drop me a line on my tumblr (same username).
> 
> Grad school starts again on monday and i am Not Ready.


	4. Refraction

**Summary for the Chapter:**

> Refraction - the change in direction of a wave passing from one medium to another

Harry had been doing so well during the beginning of term. He’d kept his mouth shut while Umbridge called him stupid, insane, and an attention-seeker. (She’d missed “freak”, he’d thought sardonically.)

But when he'd found her going off on a group of first years, he'd lost his temper.

So now he had detention every evening, and he'd had to tell Snape that they'd have to move Occlumency lessons back to end just before curfew. Snape hadn't been exactly enthusiastic about the schedule change, but he couldn't do much about it. They were both very aware that "Remedial Potions" could count as instruction outside of class, which was banned under one of the Educational Decrees. And Harry couldn't claim that Snape had given him detention at that time - he hadn't, and Umbridge would check. In fact, Snape hadn't given Harry detention since Harry's first bout of offensive Occlumency a couple of weeks ago.

So Monday night found Harry gingerly wrapping his hand in some sterile bandages that he'd nicked from Madam Pomfrey. Well, he said nicked, but he was positive that she knew and had been purposefully looking the other way. If there was one person that knew about (and reluctantly supported) Harry's do-it-yourself healthcare, it was Madam Pomfrey. Harry was sure that she'd rather that he visited the hospital wing for every injury, but she seemed to realize that an overbearing insistence on this would just make Harry less likely to visit. She treated Harry much the way that one would treat a stray cat, leaving out bandages and potions in places that made them easy to nab, and they were both satisfied with that arrangement.

By the time Harry finished wrapping his reopened wound, it was past time for Occlumency. He made his way to the dungeons, ignoring the persistent throb of his hand. He'd soak it in Murtlap Essence later. He made a mental note to look in the library for healing potions for artifact-inflicted wounds. It hadn't been a top priority, especially with the demands of starting the DA. But now the club was running itself, and the scarring was getting worse with every detention.

At the thought, he tugged his robe sleeves down until they obscured his hands. Luckily, Occlumency didn’t require the use of a wand, so he wouldn’t have to be waving his hands around all over the place. 

He entered Snape's office with a perfunctory knock. "Sorry I'm late," he told the glowering man, who surprisingly didn’t yell at Harry for his tardiness. In fact, he had only yelled at Harry a handful of times during the past few weeks. Honestly, it was throwing him off-balance. He knew how to deal with the old Snape, but this new version saw too much of Harry, and he found himself scrambling to keep his secrets concealed. He appreciated the lack of yelling, but he wasn't sure he could deal with the cost.

"I know it truly strains the bounds of your capabilities, Potter, but try to be on time," Snape snapped, but it lacked the bite it would have had a couple of weeks ago. 

Harry simply nodded in response. Snape seemed to accept that, and they moved on with the lesson.

This session, they were back to simple, direct Legilimency attacks. The Monday after the disastrous Veritaserum incident, Snape had given him the mind magic book that they had discussed. From then on, they'd fallen into a pattern - the standard, Legilimency attack method of training Harry's burgeoning Occlumency would happen on Mondays, and Wednesdays were reserved for stranger methods of mind magic training. 

They'd established a routine that Harry might even optimistically label comfortable. But last night, when Harry had woken himself up with his own screams, he'd discovered that he was out of Dreamless Sleep. He wouldn't have an opportunity to make more, not with detention, and Dreamless Sleep was one potion that Poppy would never allow him to steal.

So in the hope of a restful sleep, Harry would have to poke at the tenuous peace they'd fallen into. When Snape brought out the familiar pensieve, Harry swallowed down his nervousness, and asked - “Professor? Sir, would it… could I also…”

“Spit it out, Potter.”

Harry took a deep breath. “Could I store some memories in the pensieve as well, sir?”

Snape paused and considered Harry. “Scared of what I’ll find, Potter?”

A flash of anger burned through Harry. “I could ask the same of you, Professor.” He watched the rage build in Snape’s eyes. “But no, more like… I would like to sleep tonight. And I won’t if certain memories are dug up.”

Snape sneered at him, but didn’t dismiss Harry’s concerns. “Unfortunately, Potter, putting more than one person’s memories into the Pensieve can lead to… undesirable mixing between memories. Research is inconclusive as to why this happens, but there are a few theories I find more plausible than others.”

Snape paused. “And then, of course,” he continued, almost reluctantly, “there is the fact that offensive Occlumency is dependent on the… accessibility… of negative memories.”

“Oh.” Harry swallowed, and dipped his head in acknowledgement. 

Snape looked like he was going to say something more, before he gave a little shake of his head and gestured Harry to take his customary place on the other side of Snape’s desk. Even though Harry hadn't been able to store some of his worst memories in the Pensieve, there was a part of him that was relieved that his request hadn't collapsed their fragile peace. Well, maybe it wasn't as fragile as he had thought.

Without a word of warning, Snape dove into Harry’s mind, and Harry found himself locked, once again, in a mental battle against him.

Now that Harry understood what to do, he had a much easier time martialing his mental defenses against Snape. However, the same was true of Snape - Harry had caught him off-guard before, but now he was fully prepared for an offensive Occlumency onslaught. Harry struck at him with weapons formed from his worst memories, but Snape would pull at others to form shields or turn to smoke to escape the barrage of sharp, barbed nightmares.

It was long and painful, but Harry could feel his mind becoming more responsive, his memories quicker to react and their attacks more aggressive. However, he was also steadily losing concentration as the pounding in his head increased. Usually this happened later in the session, as Snape was winding down his attacks, but the lack of sleep last night was working against Harry. He was tiring faster than he expected.

So when Snape tore at a particularly sharp memory (there's cold, dark water surrounding him and Ron and Hermione are down there and it presses down on him, like when Aunt Petunia used to press his head down under the water a little too long, like she was resisting the urge just to hold him there until he surrendered to the urge to breathe -), Harry instinctively pushed away and tried, belatedly, to strike out at his attacker.

What he accomplished was a clumsy stumble towards Snape. His right hand lashed out in the vague direction of his professor as he tripped over the hem of his robes. He went down, and the back of his hand slammed into the edge of the desk.

His vision whited out from the pain. He couldn't move from the shock of the agony. He might have screamed - he wasn’t sure.

“Potter. Potter, look at me.”

He came back to himself with a snap. Pain was radiating from his hand up through his arm, but now that he expected it, it was manageable. Barely. 

Snape was crouched next to him, just within arm’s reach. He obediently met the other man’s gaze, and for a brief second hysterically thought that he would feel the press of Legilimency against his mind.

But Snape just nodded when Harry met his eyes, seemingly satisfied with his ability to do so. "Potter," he said in a low voice, "what was that?"

"Sorry, Professor," Harry replied sheepishly, pushing himself up to a sitting position with his good hand. His shoulder ached - he must have slammed it into the floor as he fell. "I was tired, and things just got a little mixed up in my head-"

"That's not what I was referring to," Snape interrupted. “Where are you injured?”

“What? I’m… I’m not -”

But Snape’s eyes were already roving across Harry’s body, and they caught on the hint of white peeking out from beneath Harry’s sleeve. “Your hand?”

Harry instinctively covered his right hand with his left, which, he realized a second too late, just confirmed Snape’s suspicion. 

Snape’s expression hardened. “Give it here, Potter.”

“What?”

“Your hand,” Snape snapped. “Don’t play dumb.” He held out his own hand imperiously. “Show it to me.”

“No. Sorry, no, Professor,” he hastily corrected at the sight of Snape’s growing irritation. “Honestly, it’s not that bad - I was just going to soak it in Murtlap Essence later -”

Snape waved his wand and a bowl and a vial filled with a familiar greenish liquid floated out of Snape’s personal potion cupboard. “Then there will be no issue with doing it now, will there, Potter?” Snape replied silkily.

There was no way out. Snape had effectively trapped him. Harry extended his hand to Snape with ill-grace.

Snape ignored his petulance. He flipped back Harry’s sleeve, and Harry could see that the bandages were spotted with fresh, red blood. The fall had reopened the wounds.

Snape’s mouth drew into a pinched line at the sight of the blood. With more gentleness than Harry would have expected from the dour man, Snape began to unwrap the bandages. The deeper they went, the more stained with blood they became and the more Snape’s expression darkened.

Finally the injury was revealed, although all that could be seen was a mass of inflamed skin and blood, both fresh and old and dried. Snape hissed sharply before easing Harry’s hand into the bowl of Murtlap Essence.

Neither of them spoke as Snape washed off the blood, bit by bit. The pain eased, and Harry leaned back against Snape’s desk and closed his eyes. He let himself drift for a bit, the sudden lack of pain creating an almost euphoric state.

“Potter,” Snape’s voice broke through his haze. It was filled with a crackling rage that stung Harry to high-alert. His eyes flew open and locked with Snape’s, which were dark with fury. “Pray tell - why are there _words_ carved into your hand?”

Harry was startled. Snape seemed to always know what was going on in the castle - not as well as Dumbledore and generally not in the case of Gryffindor, but Harry had heard from the Slytherins that Snape kept tabs on them and always managed to hear about wrongdoing perpetrated both by them and against them.

Harry knew for a fact that some of the Slytherin first and second years had received detention from Umbridge. He hadn’t been able to prevent those detentions in the first place, but he’d given them Murtlap Essence and cleaned their hands, much like Snape was doing for him now. Hadn’t Snape heard about the Blood Quill from them, or from the other Slytherins?

“Umbridge,” he told Snape plainly. Perhaps Snape just hadn’t seen such a bad case - the Slytherins had only had a few detentions, not weeks of it.

“And tell me,” Snape said, his voice icy, “how she did this?”

“I have to write with a Blood Quill during detentions,” Harry answered. “That’s what all of her detentions are.” And then, because he was curious - “Didn’t you hear about this?” he asked. “Hopkirk and Daniels had detention with her a week ago, and Roberts, Emilie, and Ogden the week before that.”

Snape froze. “A Blood Quill,” he repeated. His expression had smoothed into something unreadable and his voice was steady, even. Harry had the strange sense that Snape had somehow stepped beyond anger into something more dangerous.

“Okay,” Harry said, withdrawing his hand from Snape’s lax grip and drying it with his sleeve. The fibers caught on the edge of the wound and made him wince, but he could deal with that later. “So you didn’t know.”

Snape nodded, a sharp jerk of the head. “I’ll kill her,” he informed Harry. He was utterly still, calm, contained.

“Okay,” Harry replied. “But you literally can’t.”

“I can, in fact.” Snape rose gracefully to his full height. Harry scrambled to follow him, not liking where this interaction was heading. “I can think of a number of ways off the top of my head. If I restrict myself to undetectable ways, that number shrinks to… ah, about ten. Twenty.” He paused for a moment. “Eighteen.”

“Great,” Harry said. “That’s fine. Great. But can we consider that a dead Umbridge at Hogwarts will lead to a number of suspects, including, sorry for the self-interest, both Dumbledore and me. Who are definitely not the Ministry’s favorite people.”

Snape turned blazing eyes on Harry. “She is hurting students. Irreparably. Permanently.”

“Yes, sir,” Harry replied. “If it makes you feel better, I’ve received more than double the detention of any other student. So I don’t think anyone else has scars this deep.”

Somehow, that didn’t really seem to make Snape feel better. Still, the man closed his eyes and took several deep breaths. When he opened his eyes again, he looked marginally less homicidal.

"You said some of my Slytherins were in detention with her as well?"

Harry nodded, relieved at the turn of the conversation. "Hopkirk, Daniels, Roberts, Emilie, and Odgen," he listed.

Snape's eyes narrowed. "Three first years and two second years." He cocked his head to the side. "And pray tell, Potter, how you know the names of the Slytherin lower years, as well as the detentions they received? You're not a prefect, last I checked."

Harry shrugged. "I wasn't third or fourth year either."

"What is that supposed to mean?"

Suddenly Harry was in the position of explaining something that he hadn't had to find the words for before. Hermione, Neville, Ginny, and Ron had been at his side for the whole series of events, and the rest of the school had heard about it some way or another. He tried to marshall his thoughts into a semblance of order.

“Well, remember when I had all those - wait, no, I think… it starts earlier. You know how Yaxley and Tremont are friends?”

Snape snorted, settling himself in his chair behind his desk. He motioned Harry to take the seat in front of it. Harry obliged. “Of course - a Slytherin pureblood and a Gryffindor muggleborn. It caused quite a furor.”

Harry nodded. “Yeah, definitely. Neither the Gryffindor nor the Slytherin upper years were very happy about it. There weren’t any problems for the first month or so - I think everyone expected them to succumb to peer pressure and break off their friendship. But the two of them stuck together. So some of the upper years started cornering them in the halls, bullying them with really mean ‘prank’ spells.” Harry scowled. “Some of those ‘pranks’ were just this side of legal. Pomfrey couldn’t get Dumbledore to expel any of them, even when Tremont ended up in the infirmary twice in November alone.”

Snape’s eyebrows rose. “I hadn’t realized it became that severe.”

“You wouldn’t have. Most of the physical abuse was directed at Tremont. Yaxley was tormented in more insidious ways, like threatening to tell various relatives about her muggleborn friend."

Snape didn't look happy about that, but there wasn't much he could do, considering this all happened two years ago. "So what was your role in all this?" the professor wanted to know.

"I…" Harry paused. "I took an… exception to the behavior of the upper years. And I might have… uhh… dueled all of them. Until they stopped."

Snape looked at him, considering. "Was this around December, two years ago?"

Harry was surprised. "Yeah. How'd you know?"

"You had detention with Professor McGonagall until February, if I recall her griping correctly. The youngest Weasley too, if I’m not mistaken."

Harry huffed out a laugh. "Oh yeah, she wasn't too happy. She thought we should have taken it to a professor.

"I believe," Snape drawled, "that I heard the phrase 'feral hellcat' used more than once." Amusement pulled at the corners of his mouth.

"It was a couple of third years and a second year against a group of sixth and seventh years," Harry defended himself. "If we had just used magic, they would have easily beat us up."

"So you fought the muggle way," Snape supplied. 

"More or less?" Harry made a seesaw motion with his hand. "I don't think Muggles necessarily usually jump down three flights of stairs to land on the back of their target."

"You idiot!" Snape suddenly snarled. Harry reared back, taken off-guard by his outburst. "What would you have done if you had _missed_ , and instead landed on bare stone?"

Harry shrugged, which just seemed to make Snape more incensed. “It was fine,” he told the furious man. “Hermione was on hand and had her wand at the ready, and I’d grabbed some healing potions from Madame Pomfrey the day before. And if things went really bad, my accidental magic would probably kick in.”

“Children don’t have bouts of accidental magic at thirteen, Potter.”

“They don’t?” Harry frowned. “I had some that year.”

“Regardless,” Snape said, staring at Harry with a queer expression. “It was stupid and reckless.”

“Yeah,” Harry agreed, “but I got the drop on them, literally. And then Ginny followed up with a head-on assault. And they were too scared after that to fuck with me or the younger kids.”

“Language, Potter.”

“Sorry, sir.”

“So am I to assume that this isn’t entirely a thing of the past?”

Harry shook his head ruefully. “I don’t drop down on top of people now because we got better at magic and Neville learned how to throw a punch. But yeah, the lower years know that they can come to us for help with the bullies.”

“Not the prefects?”

Harry laughed. “Well, Hermione and Ron _are_ prefects now - I suppose it’s no surprise that I’m not. I’d get my badge taken away the first time a kid came to me with a split lip. But Malfoy’s also a prefect, so I suppose it all sort of evens out? Kids know who’s reliable, and that’s not necessarily someone who owns a shiny badge.”

Snape certainly noticed the slight against Malfoy, but he doesn’t say anything about it. Instead, he gestured towards Harry’s right hand, the injury still exposed. “Was _this_ part of your protection… thing?”

Harry’s always known Snape was sharp, but still, he was a little impressed. “Some of it’s my temper,” he admitted. “But yeah. She’s going after the young kids now too, but I’m still her favorite target. Most of the time, I can get her attention on me instead of them.”

Snape leaned forward in his chair. “You’ve protected them admirably,” he told Harry, his tone brooking no argument. Harry was taken aback by the sincerity in the compliment. “But protecting others at the cost of yourself is reckless and foolish.”

“I don’t really see any other options,” Harry replied. “I can’t let her do this to the lower years.”

“No,” Snape agreed. “But perhaps you can hand off your burden to someone else. You cannot guard every student - it is not possible in your current situation. Some will inevitably slip through the cracks, so to speak.” He flashed a cold, cruel smirk at Harry. “But I can and will deal with it, you can be assured of that.”

“Okay,” Harry said. He wasn’t hopeful that anything would change. Umbridge was too dangerous for any teacher to challenge alone. But he didn’t doubt that Snape was crafty enough to do something - at the very least, maybe he wouldn’t have to worry about the Slytherin kids. And maybe even Snape would do something about the mostly-Slytherin Inquisitorial Squad.

Still, Harry was going to go look up those healing potions in the library. He didn’t foresee the detentions stopping anytime soon. But Snape did have a point… a few more pairs of eyes, a few more people willing to intervene….

Snape nodded firmly, and Harry got the strangest sense that Snape knew the direction that his thoughts had turned. “You’re dismissed, Potter,” Snape said, turning to mess with something behind his desk. Harry couldn’t see anything from his vantage point. “Go see Madam Pomfrey.”

“Yes sir,” Harry replied. Sure, he’d go to Madam Pomfrey - he did need more bandages - but he had a few stops to make before that.

**Notes for the Chapter:**

> Another week, another chapter posted. I'll slow down a little after this until I finish the next chapter. I have two more in reserve, but well... Grad school is grad school and I'm also trying to get my original short fiction published. (I got two drabbles accepted somewhere, so my year's starting off well on that front.)
> 
> Thank you all for your support!! Your comments always brighten my day! find me on tumblr at the same name. (or on my server for my bnha fic Subject: A Comprehensive Report)
> 
> thank you to astahfrith for beta'ing!


	5. Shock

**Summary for the Chapter:**

> Shock wave - a type of propagating disturbance that moves faster than the local speed of sound in the medium

Snape had given Harry an idea - hand off his burden to someone else. He wouldn’t do that, of course, but the truth was, he _couldn’t_ be everywhere at once. But Harry did have a rather large number of very pissed-off teenagers that he hung out with a couple of times a week. At the next DA meeting, he brought up the issue, and immediately had a small squadron of anti-Umbridge students to combat her Inquisitorial Squad. He had emphasized that the priority was the safety of the lower years. Harry didn’t trust that they’d remember that once they got a taste of revenge against Umbridge, but he trusted Ron and Hermione to keep them on track.

“Didn’t expect that,” Neville said to him in an undertone as the DA filed out of the Room of Requirement.

Harry shrugged. “Someone pointed out that I can’t do this by myself.”

Neville slanted an amused look at Harry. “Who? Me? Hermione? Because I’m amazed that you finally noticed, really. It’s only been five years.”

“I ask you guys for help all the time!” Harry protested. “You were the original… whatever this is. Anti-Bullying Squad.”

“Yeah,” Neville agreed. “And while we were punching bullies, you were doing death-defying stunts to… I don’t know, freak them out? I was never really clear on your logic.”

“It worked,” Harry defended himself.

“Somehow it did,” Neville conceded easily. “But you broke at least three bones that first year.”

“And then I got better!”

“At avoiding injury?” Neville shook his head. “No, we just got better at preventing it.”

“Hey!” Harry protested.

“One time Ron said ‘oops’ on the stairs,” Neville continued, matter-of-fact, “because he remembered some homework he’d left in his room, and Hermione had three cushioning charms on the ground before he could blink. It’s a reflex now. She does it in her sleep.”

Harry couldn’t argue with that, so he didn’t even try.

“I know that these extra people won’t actually stop you from trying to get yourself killed,” Neville said wryly, “But honestly Harry, this is a step in the right direction. What really convinced you?”

Harry paused. His need to keep things close to his chest, to hide and conceal, warred with his desire to be honest with Neville, who had always been honest with him.

As had gotten more and more common throughout his time at Hogwarts, his friendship with Neville triumphed. “When Snape says the same things that your friends have been saying for years, I think it’s a sign that it’s time to listen.”

Neville was stunned silent, his eyes wide and his mouth hanging open. “Snape?” came a voice behind him. Harry turned to see Ginny approaching, her auburn hair gathered up in a messy bun. “Really?” she asked, visibly amused. “That’s what it took?”

“You have no leg to stand on,” Harry pointed out. “You also broke three bones that first year.”

“Fuck yeah I did,” Ginny said, and offered up a fist bump. Harry gently knocked his knuckles into hers. “Feral hellcat club.”

Neville sighed and massaged the bridge of his nose, but he didn’t protest. None of the others ever did, not really.

Harry was grateful for their support in ways that he couldn’t express. He’d come back after second year with screaming nightmares of fangs, of eyes in the darkness, of hands and veins full of fire. He was a phoenix in human skin, burning every night and reassembling himself from ashes every morning. 

Ginny had come back half-dead. Pale and quiet, she saw ghosts where no one else did. Only Harry knew about Tom, knew the way that memories could haunt you. 

That year, they’d run through the castle at night together, exploring every nook and cranny, avoiding patrolling teachers. The others knew about these excursions, but none of them ever tried to stop it, not even Hermione. The threat of Sirius Black had been hanging over all of their heads, but somehow that wasn’t as terrible as the things that stalked Harry and Ginny in the silence, and their friends had understood that.

It hadn’t been enough after a while, and all of them were aware that Harry’s campaign against the bullies started partly out of compassion and partly as an outlet. Harry and Ginny had thrown themselves at enemies that they could confront, that they could win against, with a fervour that had frankly scared Neville and Hermione. Ron had approved, but hadn’t been able to muster the same sort of aggression as Ginny or Harry. Both of them had calmed down eventually, but Harry knew that the others still carefully monitored them for signs of self-destruction.

Honestly, that sort of scrutiny was probably wise. Harry didn’t particularly like it, and it chafed occasionally, but he knew that of all the students who had been provoking Umbridge, only he and Ginny had a phrase that would scar. It was just smart of their friends, really.

“But honestly, Harry,” Ginny continued. “Snape? He actually gave you real advice? That you actually decided to follow?”

Harry shrugged, a little uncomfortable. “I don’t know. He’s not… He’s weird now.”

Ginny snorted. “Wow, that’s descriptive.”

“Well, I don’t know, Ginny,” Harry snapped. “I did some Occlumency unexpectedly that like, is common if you have a fucking heap of bad memories. So Snape figured out that I do. Have bad memories, that is. And somehow that shook his worldview? But also made him really invested in me doing well in Potions. I really don’t know, okay? He’s being weird.”

“You are good in Potions,” Neville pointed out, like he always did.

“Memorization,” Harry snapped back automatically.

Neville sighed. “Harry, memorization requires intelligence as well.” It was an old argument of his and Hermione’s. Harry appreciated their efforts, but really, he wasn’t smart. They didn’t have to try to convince him that he was.

Ginny had a thoughtful look on her face. “It sounds like he’s trying to observe you and your actions without bias.” The _finally_ went unspoken.

Harry shrugged. “I guess.” He paused. “I don’t like it.”

“What?” Neville asked incredulously. “You preferred him yelling abuse at you every class?”

Ginny snorted at the look on Harry’s face. “Of course he did, Neville. It was easier.”

“Easier how?” Neville demanded.

Harry and Ginny didn’t answer him, but they shared a look. Ginny understood - when Snape hadn’t been looking, it had been easier for Harry to keep his secrets.

“Easier doesn’t mean better,” Ginny finally stated.

“Sure,” Harry agreed. “But harder doesn’t mean better either.”

“I think we can all agree that cryptic, however, is _the worst_ ,” Neville broke in.

Harry huffed out a laugh. “Yeah, Neville, sorry.”

Ginny slung an arm over Neville’s shoulders. She missed the hint of a blush on Neville’s cheeks, but Harry didn’t. “Sorry to leave you out, Neville.” She knocked their foreheads lightly together before she pulled away. Harry ducked his head to hide an amused smile.

On the way back to the common room, Harry pulled away from the group. He waved them all on their way when they paused. He had found some healing potions in the library that looked promising, and he already knew that tonight would be a bad one. If he wasn’t going to be sleeping anyway, he might as well do something productive.

He made it to his favorite abandoned classroom without incident. It was an unfurnished room in the basement with a high ceiling. He had realized sometime during fourth year that it had actually been the room with the Devil's Snare from Dumbledore's death trap his first year. He could even still see bits of the old scaffolding for the plant embedded in the walls. The high ceiling was a boon when venting potion fumes, so Harry didn't let himself be disturbed by the memories the room evoked.

He set up his cauldron efficiently and then surveyed the potion recipes and his stock of ingredients. All of the potions called for at least one ingredient that Harry didn’t have access to, either because they were illegal, expensive, obsolete, or all of the above. But these were old recipes, and Harry figured that he could find a substitute for the missing ingredients. There were many more potion components available nowadays, thanks to international trade and improved harvesting and culturing techniques.

Harry decided to start with a potion labelled just labelled “dolhdrenc”, which he knew from his studies of Futhark meant “a potion to heal wounds”. Unfortunately, the translation that Harry had found seemed to be poor quality. Some of the suggested ingredients would certainly lead to an explosion if combined. Harry wished that the library had also included a copy of the book in the original Old English so he wouldn’t have to muddle through the mess the translator had made, but only this translation had been available. Harry had to backtranslate the ingredients to figure out where the original translator had gone wrong. Eventually he realized that the translator had probably interpreted instructions about the species of plant needed as a suggestion of the location of different members of the nightshade family.

After a couple of hours of work, Harry had a completed recipe that he was more or less happy with. He had substituted the unwillingly taken unicorn blood (he’d had an unpleasant flashback about Quirrell when he’d seen that ingredient in the list) for a combination of remora scales, peacock flower seeds, and hippogriff blood. It was a common substitution nowadays, but the fact that there were three additional ingredients required that Harry be extra careful in checking that none of the original ingredients would react unpleasantly with them.

Harry’s chicken scratch was blurring in front of his eyes. He lifted up his glasses to rub his aching eyes. He was tired and he had a headache, but he still wouldn’t be able to sleep, so he decided to proceed.

Everything went smoothly until Harry hit the ninth step. He was adding the newt eyes, one by one. He plopped in the fourth, stirred counter-clockwise -

He was on the floor, somehow on the other side of the room. His ears were ringing and his back was a mass of pain. He tried to sit up, but he couldn’t get his arms to cooperate with him. He shook his head and tried to focus on his surroundings, but everything was blurry. The air smelt of burning herbs. He coughed, and something ached in his chest. He blinked.

He was on his back again. There was something dark swimming above him. He heard a faint sound under the ringing in his ears. He blinked.

There were gentle hands on his aching body. His ribs twinged with pain. The world was swaddled in blackness. He blinked.

There was cloth against his cheek and he was moving. Someone was carrying him. He tried to ask what was happening. He croaked out something before his throat hurt too much for him to continue. He heard a voice say something in response, but the ringing was still louder and the words escaped from him like water running through his fingers. He blinked.

White surrounded him. The familiar scratch of bandages pressed against his chest when he coughed. “Whym... “ Harry choked out. “Hos… pital… wing?”

The dark figure returned to loom over him again. “Just go to sleep, idiot child,” Snape snapped. His voice was thick with some emotion that Harry was too tired to understand. “You can explain yourself in the morning.”

Harry tried to nod, but his eyes slipped shut halfway through the motion. He slept.

* * *

Harry woke several times throughout the night in a haze of pain. Someone would pour a couple potions down his throat, and then he’d drift back to sleep.

He finally woke up fully when sunlight was streaming through the window, lighting up the white walls of the hospital wing. After a moment of confusion, he realized what must have happened. He’d messed up the potion in some crucial way, either through his translations or his substitutions, and it had exploded violently. Someone had found him and brought him to the hospital wing.

And unless those memories were part of a feverish hallucination, that “someone” was….

“Potter.” Snape strode into the hospital wing, a crate of potions cradled in his arms. He set it down on the floor near Pomfrey’s office door and stalked towards Harry’s bed. He pulled up a nearby chair and sank into it. “You’re awake.”

Harry nodded, even though it hadn’t been a question. “Just now, yeah.”

Snape nodded and looked down at his hands, which were clasped in his lap. After a moment, he raised his head and locked furious eyes on Harry.

“What,” Snape bit out, as angry as Harry had ever seen him, “were you thinking, Potter?”

Before Harry could do more than open his mouth, Snape barrelled on, “Nevermind. You _weren’t_ thinking - that’s more than clear. But what in Merlin’s name possessed you to brew an experimental potion, alone and after curfew? Could you have possibly chosen a more foolhardy late-night activity?”

“It wasn’t experimental,” Harry protested. “I found it in a library book.”

“What potion was it, then?” Snape snarled. “Because I certainly didn’t recognize it.”

“It was called _dolhdrenc_ , which I know isn’t specific, but I don’t know what the modern -”

“You found it in a book written in Anglo-Saxon,” Snape said, voice flat.

“Well, no,” Harry corrected. “It was translated into Modern English, but the person didn’t translate it well, so I translated it back into Anglo-Saxon, and then I -”

“There were three translation steps.” Snape seemed to have moved beyond emotion. His face was blank. Harry was uncomfortably reminded of when Snape had gotten homicidally mad about Umbridge’s detentions.

“Well… yes.” Harry paused. “And a substitution for unicorn’s blood,” he said as quickly as possible.

“A… substitution,” Snape repeated.

Harry swallowed thickly and nodded.

“I cannot think of a potion that better fits the description of experimental than the brew you were attempting,” Snape told him. His words were flat, precise, sharp. “And yet you had no precautions. No assistance. No shields. None of your friends even knew where you were brewing.”

Harry looked down at the hospital blankets. “I’d done it before.”

Snape ignored him. “That still doesn’t explain what possessed you to embark on this moronic endeavor. What was so vitally important that you had to brew it at that time of night?”

Harry shrugged. “It was… I just wanted to brew a potion to heal the blood quill wounds. For the people who get detention.”

“That does not sound like something that required you to brew after curfew.”

“I wasn’t going to sleep that night anyway,” Harry weakly defended himself. “So, you know. Might as well do something productive.”

Snape was silent for a long, long moment. His lips were pressed into a bloodless line and his hands were clenched in his robes. “Detention,” he finally bit out. “For two months.”

“What?” Harry cried. “Two months?”

“What?” Snape snapped, his calm exterior finally breaking to show the rage beneath. “You think that’s too much? Oh boo hoo, Harry Potter has to attend detention for two months after he almost blew off his own head! Oh, how unfair Professor Snape is, giving precious Potter detention for creating an unstable potion that could have separated his rib cage from the rest of his body!”

“It wasn’t that bad!” Harry protested.

“The fuck it wasn’t,” Snape snarled. “Potter, it blew a three-inch deep depression in the classroom wall! The only reason you aren’t a smear on the floor at this very moment is because your magic automatically redirected the blast away from you!”

“Oh,” Harry breathed.

“Oh,” Snape mocked. “Yes, Potter, ‘oh’. You could have died in that room, without anyone the wiser. So you’ll be in detention with me for three months, where we’ll be discussing the precautions that must be implemented when brewing an experimental potion. And since you’re so industrious about experimentation, you can help me with some of mine.”

“Three months?” Harry said. “I thought it was -”

“An extra month for complaining about your detention. Do you want me to make it four months?”

Harry shook his head. After a moment, he dared to ask, “What about… Remedial Potions?”

Snape smirked. “I don’t see why you can’t have detention on top of your remedial classes. You seem to have enough free time to get in trouble.”

Harry scowled at him. Snape sneered back and rose in a flurry of robes. “7pm, Potter,” he demanded. “Every night, including weekends.”

“I have homework! It’s my OWL year!”

“You should have thought of that before you almost killed yourself,” Snape snapped. “7pm, my office.”

“Fine,” Harry replied mutinously. He didn’t think this was worth three months of detention. Sure, it had been stupid of him to brew alone, but all of this seemed like an overreaction. Harry had been in danger, sure, but he hadn’t died, had he? It wasn’t like this had been the first time he’d done something like this, and it had been fine every other time.

Snape gave him one last disdainful look before sweeping out of the hospital wing, his robes billowing behind him.

Soon after, Madam Pomfrey emerged from her office to discharge Harry. Her disapproval was clear in every line of her body. Harry actually felt a little guilty for being such a burden on her. All she wanted was for him to avoid the hospital wing, and he kept needing overnight stays.

It was clear that she wanted to keep him under observation for a little while, but she knew that Harry would chafe under the restriction. So she signed him out, with pointed comments about taking care of himself. She also sent a couple of weird glances at Harry’s right hand. Which, yeah, that reminded him - Harry nabbed some bandages and a couple of Blood Replenishers and bottles of Murtlap Essence on the way out.

By the time he got out of the hospital wing, it was already lunch. He made his way to the Great Hall and was greeted by the exclamations of his friends.

“Mate, what the hell happened?” Ron asked. “We woke up and you weren’t there this morning. And then Snape of all people stomped into the dormitory to ask if any of us knew where you’d been. I wasn’t even fully dressed!”

“Sorry about that,” Harry replied sheepishly. “Yeah, the potion I was working on last night didn’t… well it wasn’t a success. And Snape found the aftermath and took me to the hospital wing. He was boiling mad about it. Sorry you got caught up in all that.”

“Wasn’t a success?” Neville asked at the same time Hermione questioned, “Mad in what way?”

Harry chose the safer of the two questions. People had yelled at him enough this morning, thank you very much. “I don’t know,” he answered Hermione. “It was weird. He started off establishing that the potion I was working on fit the description of experimental, and then was like, you didn’t use proper precautions, and then he starting yelling about how I could have died and then he gave me _three months_ of detention. In the middle of OWL year! Three months!”

“You could have died?” Neville asked. Harry pretended not to hear him.

Hermione nodded firmly. “That fits with what I observed this morning.” She turned a contemplative look on Harry. “He was _worried_ about you.”

“What?” Harry asked, stunned. “No, Hermione, he really wasn’t. He was angry, not worried. Three months of detention doesn’t say ‘worried’ to me.”

“Those are really the same thing,” Ron explained. “Like when the twins were messing around with runespoor venom in the house, and Mom got blazing mad, because they could’ve poisoned themselves.”

“What do you think anger means?” Ginny leaned forward to ask him.

“I mean,” Harry explained haltingly. “Adults get mad when you’ve… when you’ve been an inconvenience? And a burden? And interrupted things they were doing to make them deal with your problems?”

His friends were silent for a long moment. “So when we were angry at you after the Philosopher Stone debacle,” Hermione finally said, “why did you think we were so mad?”

Harry felt off-kilter, like he’d missed a step on the stairs and now there was only air beneath him. “Because… because I dragged you into it?” he ventured.

Hermione sighed and buried her head in her hands. “We should have communicated better,” she said, her voice muffled. “Maybe we could have entirely avoided second year.” She lifted her head to stare Harry straight in the eyes. “Harry, we were mad because we were worried for you. We were angry you put yourself in danger in the first place, not because we accompanied you. Willingly, I’ll add. The anger stemmed from our care for you.”

“You know, someday I’ll kill your relatives,” Ginny remarked blithely. (“Get in line,” Neville muttered under his breath.)

“So…” Harry asked, “are you angry now?”

“Yes-”

“Definitely.”

“Absolutely livid,” Hermione confirmed. “And if Professor Snape hadn’t already yelled at you, we would have. We let you go off and brew alone because we thought you were putting up shields and taking the same precautions you do when you’re doing experimental potions in class. Lord knows you’re good enough at Runes to ward a potions room securely.”

“When I’m brewing alone, there’s no one to get hurt,” Harry explained. “So I didn’t really think about it.”

“There’s you, you doofus,” Ron said, and then grabbed Harry in a gentle headlock so he could vigorously mess up his hair. But Harry didn’t miss the range of expressions on his other friends’ faces. Ginny looked murderous. Hermione’s expression was despairing. And Neville - Neville looked heartsick.

“I’m - Ron, Ron, stop it - guys, honestly, I’m fine. It’s fine,” Harry reassured them.

Hermione nodded. “We know. And you won’t do it again, will you, Harry?”

“I don’t think Snape would let me,” he told them truthfully.

Hermione flashed Harry a thin smile. “No,” she replied. “I don’t think he would.” Harry had the unsettling feeling that there was a joke that was going over his head. He wondered what he was missing.

Later, after a nightmare had pulled him into screaming wakefulness, when the world was soft and dark with the anticipation of sunrise, Harry got the joke. Snape had been angry like he cared about Harry, but Snape had never cared about Harry. So yeah, that was pretty funny.

But somehow, Harry didn’t really feel like laughing.

**Notes for the Chapter:**

> thank you all for your support! I'm so glad so many people are enthusiastic about this fic!
> 
> Thanks to astahfrith for betaing!
> 
> Sorry this one was late, and sorry in advance for the delay on Chap 6 - I haven't finished Chap 7 yet. Why? because the depression hit like a motherfucking wall. i'm still.... in the depress..... and it's impossible to write much. and my limited energy is going to origfic because i want to submit a short story for publication this year dammit.
> 
> BUT thank you for all your support!! It means so much, especially during the Times <3


	6. Reaction

**Summary for the Chapter:**

> Reaction force - a physical force that is the result of an equally strong physical force in the opposite direction

“We will start,” Snape said, “by reconstructing _exactly_ what you did and where you went wrong.”

“Why?” Harry asked, a little petulantly. “I messed up. Can we move on?”

Snape sneered. “No, Potter, we cannot. Are you so content to simply live with whatever alterations your failed potion may have produced in your body? Are you so arrogant to believe that the effects were merely cosmetic?”

“What do you mean?” Harry asked, confused. “Alterations? Cosmetic?”

Snape’s eyes widened. “Did you not notice?” He gestured to Harry’s right hand.

Harry obediently looked down at his hand. He didn’t notice anything different. Same brown skin, bony, crooked fingers, the scars from Umbridge which read… wait.

It became hard for Harry to breath. The air was whooshing out of his lungs faster and faster, but he couldn’t slow the frantic pulse of his chest. Instead of “I must not tell lies”, there was a delicate line of runes across the back of his hand. He couldn’t make out what runes they were because his vision was getting blurry as the panic rose in his throat. His legs dropped out from under him.

There was a pressure on his shoulders and a baritone voice saying something to him, but he couldn’t concentrate on anything but the thought that _the potion had changed him_. He knew the horror stories about potion accidents and the debilitating conditions they could lead to. He just hadn’t thought it could happen to him.

Suddenly the world went dark. He was still breathing far too quickly, but the scent of cloves and black tea enveloped him. There was a hand covering his eyes, the fingers long and callused. Another hand lifted his left hand to press against scratchy robes. He felt the rhythmic rise and fall of the chest beneath his palm. Gradually, his breathing slowed to match.

As the panic drifted away, Harry came back to himself. He realized exactly what position the two of them were in, and he felt a deep flush of embarrassment suffuse him. “S-sorry,” he stuttered, pulling back from Snape. “I didn’t… Sorry. You didn’t have to -”

“Spare me your babble,” Snape said. He rose gracefully to his feet and dusted off his knees. He offered Harry a long-fingered hand.

Harry could still feel the shakiness in his limbs, so he swallowed his pride and took the offered help. Snape levered Harry to his feet with surprising strength.

“As I was saying,” Snape said, forcing the situation back to something resembling normalcy, “our first task is to reconstruct your failed brew. Do you require a calming potion?”

Harry shook his head, still flushed with embarrassment. “I’m fine, sir. Sorry for -”

“Don’t apologize. Now, what recipe were you using?”

“I wrote down the whole thing,” Harry replied. “It should be back in the Philosopher room.”

“What room?”

“Oh, yeah, sorry - the classroom I was using. It was part of the gauntlet that protected the Stone -”

“I know that,” Snape interrupted. “But if that was the only copy of your procedure, then it’s little more than dust now.”

“What?”

“What about ‘three inch depression in the wall’ do you not understand, Potter?” Snape snapped. “Your cauldron was obliterated. Your prep table is a pile of splinters. The only reason your bookbag survived is that you happened to land near it when your magic shielded you from the majority of the blast.”

“Oh,” Harry replied dumbly. He hadn’t really considered the full extent of the damage. But now that he realized - “I need a new cauldron,” he told Snape.

Snape gave him a familiar smirk. “No, Potter,” he said, his voice dripping with smug satisfaction. “As you have no access to Diagon Alley at this time, I’ve kindly deigned to lend you one of my own personal cauldrons. However, since I don’t wish it to be destroyed, it can only be used in the classroom or in my personal laboratory. You can’t take it with you, unfortunately.”

“You - you can’t do that!” Harry sputtered.

“Would you prefer to have no cauldron at all? You would certainly fail Potions, as I can’t possibly grade -”

“I can get one from Hogsmeade!” Harry interrupted. Using a cauldron only under Snape’s supervision would be a disaster. There were potions that he needed to brew that Snape wouldn’t approve of - most importantly Dreamless Sleep. Harry wasn’t _addicted_ to it; he was very conscientious of his use of it. Still, he doubted that Snape would just let him brew batches of it, even if he told Snape he made sure to only use it twice a week at most.

“The next Hogsmeade trip is in three weeks,” Snape bit out. “And if you desire to visit the village at times outside of designated field trips, you need a teacher’s permission, which I _refuse to give you_.”

“Why not?” Harry demanded.

“You. Almost. Killed. Yourself,” Snape snarled, pounding his desk to punctuate each word. “I cannot comprehend why you seem unable to recall this one crucial piece of information. Even if you were to buy thirty cauldrons and have them flown by a flock of owls to Hogwarts, I would not allow you to brew without supervision. Let’s dispense with any pretenses, shall we? I simply find it easier to control your access to a cauldron rather than your use of your personal one.”

Harry laughed, the sound devoid of humor. “Why on earth is this such a big deal?” he asked Snape frankly. “You keep emphasizing that I almost died. Yeah, I know, and next time I’ll put up ward stones or something, I get it. But I’ve almost died loads of times, and this one isn't even that bad. It’s not like anyone’s banning me from touching goblets or going to the bathroom or petting rats.”

Snape blinked at him. “What does any of that mean? Bathroom? Rats?”

“It doesn’t matter!” Harry barrelled on. “My point is that I almost die a lot! I don’t see why you’re making such a fuss over this!”

“Just because others have failed to reprimand you for your reckless behavior does not mean I will, Potter!” Snape snapped. “It is a ‘big deal’, as you so charmingly put it, because it is a situation in which you were in peril. The fact that other life-threatening situations were treated with levity does not mean that this one deserves to be similarly dismissed!”

Harry paused and tried to wrestle his anger under control. He still didn’t understand where Snape was coming from, but it was clear that protesting was getting Harry nowhere. He couldn’t tackle this head-on. “Fine, sir,” he acquiesced. “I understand.”

Snape eyed him dubiously, obviously suspicious of Harry’s quick capitulation. But he was unwilling to press Harry further on the issue, so with a flare of robes, he stalked to the blackboard positioned behind his desk. Harry could see the half-erased ghosts of a dizzying array of calculations on it, all in Snape’s precise script.

With a tap of Snape’s wand, they all disappeared, and the board was pristine again. Snape handed a piece of chalk to Harry. “Write what you can remember,” Snape demanded. “And mark the place where the potion exploded.”

Harry dug the library book out of his bag and flipped it open to the poor translation of the dolhdrenc potion. Over the next hour, he reconstructed his potion. He realized as he was writing it out that he might have backtranslated and then retranslated step four slightly incorrectly, as he had added four drams of singing pea instead of four drams of singing pea leaves. He put both the correct step and his mistake on the board. He also marked step nine, the gradual addition of newt eyes, as the moment of explosion.

With a satisfied nod, he stepped back and surveyed his work. He turned to Snape to announce his completion of the recipe, only to find his teacher standing stock-still behind him, eyes fixed on the board.

“Have you been there the whole time,” Harry tentatively asked, “or did you just -”

“Why in Merlin’s name did you think this was a good idea?” Snape interrupted. “There are at least five pairs of ingredients in this procedure that, as far as I am aware, no one has tried combining before.”

“I… I didn’t see any hostile pairs in this,” Harry contributed. “And remora scales, peacock flower, and hippogriff blood is a common substitution -”

“Peacock flower is a South American plant,” Snape cut him off. “Tell me, if you would be so kind, how it reacts with yarrow. I ask, you see, because I can assure you that the European potions community has absolutely no idea. No one has thought to try it, because _it doesn’t make sense_.”

“It does,” Harry argued, “because the seeds of the peacock flower are an abortifacient, which imbues it with a sense of death of new life, and it’s strongly sun-linked. Yarrow is used to staunch the flow of blood from wounds, so life from the jaws of death, and it’s also sun-linked, but in an opposite direction. So they would cancel out, more or less, except for the newness and birth aspect of the peacock flower -”

“Except that a similar process is occurring with the peacock flower and the hippogriff blood and remora scales,” Snape interjected. “That’s why it’s a _substitution_ for unwillingly taken unicorn blood, Potter. Because together, they mimic the symbolic weight and the properties of unicorn blood. The peacock flower can’t serve both purposes.”

“I’m not saying it does,” Harry replied heatedly. “But you said - anyway, that doesn’t matter. What does matter is that peacock flower shouldn’t react negatively with the yarrow, especially since it’s reacting with the rest of the ingredients in the triad substitution -”

“The triad substitution is not as robust as its creator made it out to be, Potter!”

“I know that! But let’s say it was reacting with the yarrow in an off-target manner -”

“Yes, let’s say that, instead of reacting with, say, the singing pea, which you _mistranslated_ -”

“You were the one who brought up yarrow!” Harry cried, frustrated. “I’m just trying to respond to that!”

“It was an example, you foolish b--” Snape cut himself off. “You foolish child!”

“I know it was reckless!” Harry shouted. “But I thought we were trying to figure out what went wrong instead of you just telling me how stupid I am!”

“Don’t raise your voice at me!” Snape snarled.

“It’s the only way to get you to hear me, apparently!” Harry snapped back, but the moment the words left his mouth he knew he had messed up. Snape’s face darkened in anger and he took a threatening step towards Harry.

Years of reflexes kicked in and Harry threw up his arms to protect his head and cringed back from the expected blow.

It never came. Harry uncurled himself, once again overwhelmed with embarrassment, only to find Snape staring at him, something haunted in his gaze.

He looked far too understanding. Harry had the terrible thought that maybe Snape-the-teenager had also flinched at angry men. He didn’t want to ask. And he certainly didn’t want Snape to ask him either. “Sorry, sir,” he said eventually, firm enough to be a definitive end to a conversation that never began.

Snape nodded in acknowledgement after a moment. It wasn’t an apology, but it was something close. He took a deep breath and let it out slowly.

“We will,” Snape said after a moment, his demeanor forcibly calm, “be experimenting with the components of this experimental brew on Tuesdays and Thursdays. Mondays and every other Wednesday will still be devoted to Occlumency. As for Fridays and the weekend, I will have you assist me with my own experiments.”

“I have detention on the weekends too?” Harry asked, dismayed.

“Three months of detention, Potter. You no longer have Quidditch practice or any Quidditch games, so your weekends should be free. Are they not?”

Harry narrowed his eyes, suddenly suspicious. “Is this so that Umbridge can’t -”

“This is because of your recklessness,” Snape interrupted.

Harry nodded slowly. “As you say, sir.”

“Don’t give me cheek, Potter, or I’ll take yours to use in my weekend potions.”

Harry snorted. “What are the properties of human cheeks? Alkaline, oily -”

Snape huffed out something that sounded suspiciously like a laugh. “I dare not speculate. I fear you might try to incorporate them into your next brew.”

“Better or worse than peacock flower seeds?”

“Get out of here, Potter,” Snape replied, seating himself at the desk and waving a dismissive hand at Harry. “Be here tomorrow and try not to kill yourself in the meantime.”

“I do try, sir. Goodnight.”

“Goodnight, Potter.”

* * *

In the Occlumency book that Snape lent Harry, the author discussed “gemearr selflic”, literally translated as “instinctive obstruction”. The broad concept was that the Occlumens should develop an automatic negative response to an invasion by a foreign mind. Thus, when the Occlumens was distracted (or sleeping), the mind’s defenses would still strike out at an unfamiliar presence.

Harry and Snape had been working on Harry’s ability to do this instinctive obstruction, generally by Snape either attacking him with Legilimency unexpectedly or Snape introducing new challenges for his mental defenses to deal with during their Wednesday sessions. The Wednesday sessions felt productive, but it had been getting more and more difficult for Harry to instinctually react to Snape’s mental presence. He had worried, when he was alone, cocooned in the darkness of his bed, that perhaps he was somehow getting _worse_ at Occlumency. Snape didn’t seem fed-up with the speed of his progress, but he also didn’t seem particularly happy about it either.

The problem with the instinctive obstruction technique was that Harry wouldn’t know if he had succeeded. For weeks, he had slept as normal - terrible nightmares, but no dreams of snakes or corridors. His instinctual defenses didn’t activate. He didn’t know if it was a result of complete success or if Voldemort was just staying out of his head. One, of course, was far more likely than the other. But still, the uncertainty only bolstered his anxiety and worsened his nightmares.

But tonight, after Harry had drifted into an uneasy sleep, he was woken by the activation of his mental defenses. After a moment of bleary confusion, he realized what was happening, and, interestingly, why it had been so difficult to keep Voldemort out in the first place.

When Snape had begun training him in Occlumency, Harry had perceived him as a foreign presence, an intruder, a glaring blemish on the mental expanse of Harry-self. But Voldemort was something more familiar, more insidious. Like the scent of rot, terrible, sickly-sweet, and pervasive. He felt like something that Harry had known all his life.

But Snape had been training him to react against the almost-normal, almost-self, and Harry realized with a jolt that during the latest Occlumency sessions, Snape hadn’t been a glaring stain on his mental world, but a faint shadow, trailing smoke and silver. Harry knew the touch of his mind better than any other. He hadn’t been getting worse at Occlumency - Snape had just been becoming more familiar.

When Harry drove his memory-weapons into Voldemort, he _screamed_. It felt so good. Harry took his vengeful satisfaction and wrapped it around his weapon. He stabbed the rot-touch of Voldemort’s mind again and again and again. Before the other wizard could fully recover, Harry tried to shove him out of his mind, hard.

Voldemort resisted. He dug mental claws into the soft bits of Harry’s mind and stubbornly held on. But Harry was even more stubborn. He stabbed and hacked and finally gave one final, almighty _push_. Voldemort tumbled out of his mind.

But the push destabilized Harry too, and somehow he found himself also stumbling. He did the mental equivalent of tripping backwards, and suddenly he was falling -

He landed on what felt like solid ground. He breathed in with lungs that didn’t exist. There was a sense of cool earth against his body and the scent of fallen leaves, crisp with the bite of oncoming winter. He rolled onto his back and opened his eyes.

The sky above him was a riot of stars, more than he’d ever seen in his life. The smoky band of the Milky Way was a bright road across the expanse of the night. It took Harry a moment to find any familiar constellations - the multitude of stars made it difficult to locate any specific one.

The world around him was quiet. All he could hear was the brush of the breeze against the tall grass. A cricket chirped in the distance, faintly.

“Where am I?” he whispered to himself. He stretched his hand up towards the stars and pretended like he could touch them.

“This, Mr. Potter,” said Snape, settling himself beside Harry, “is my refuge.”

Harry glanced at the man next to him. He couldn’t make out any details in the shadowy darkness, but he heard Snape lie down next to him.

“It’s beautiful,” Harry told him. The words seemed inadequate somehow.

Snape hummed in agreement. They stared at the stars together for a time. Harry felt a bone-deep peace suffuse him. He wished he had something like this as his refuge, and not his terrible cupboard.

“Why are you here?” Snape asked him finally. Harry didn’t know how much time had passed. Snape’s voice was soft and slow, like it was also weighed down by the peacefulness of this place.

“I pushed Voldemort out of my mind, but then I stumbled,” Harry told his teacher. “I stumbled, and then it felt like… I fell backwards? Or something? And then I ended up here. I don’t know how that happened.”

He heard Snape sit up. “You successfully repelled the Dark Lord?” he asked, a strange mix of dread and glee in his voice.

Harry nodded, and then remembered that Snape wouldn’t be able to see it. “Yeah. I think I took him by surprise. But I noticed him, finally, and then I stabbed him and pushed him out.”

Snape laughed, incredulous and a touch wild. “You repelled the Dark Lord,” he repeated.

“Yeah, I mean, I thought this was the goal of all of this?”

“Yes, eventually,” Snape agreed. “But we have been studying Occlumency for about a month and a half, and only in the last four or so weeks has the instruction been productive. Occlumency for a month and you were able to push out the Dark Lord. Do you -” He paused. “No, of course you don’t. Potter, I was expecting you to accomplish this after half a year of instruction. And even that estimate was wildly optimistic.”

“The hardest part was finding him,” Harry explained, still confused by Snape’s amazement. “Because he was so familiar. But once I figured out that he was the smell of rot -”

“What?”

Harry huffed out a breath. “You know when there’s rotting food in the fridge?” He paused. “Wait, no, maybe not -”

“Potter, I am aware of refrigerators. Please continue.”

Snape, aware of muggle appliances? That was a strange thought. Harry tabled it for later. “Yeah, so, rotting food,” he continued. “The whole kitchen starts to smell a little off, a little sweet. But you get used to it, so it doesn’t register. That’s just how the kitchen smells now. Until you open the fridge and get a blast of the stench, and then you realize that the kitchen has been stinking all along. It’s like that, you know? I just opened the fridge.”

“That’s a terrible metaphor, Potter,” Snape said. He sounded amused.

“But effective!” Harry chirped. 

Snape sighed. Harry counted it as a victory.

They lapsed back into silence. The wind rustled the grass. There was a distant cry of a bird.

“What do you see me as?” Snape suddenly asked. “When I invade your mind. You saw the Dark Lord as rot, yes? You’re obviously familiar with my mind as well, since you ended up here. What am I?”

Harry thought for a long moment how to verbalize it. It wasn’t something that he’d tried to articulate before. As he stared up at the vast expanse of the sky, it came to him in a flash. “Stars,” he declared.

“Stars?” Snape repeated, confused.

“Stars,” Harry answered definitively. “You’re like… a trail of silver, both close and far away, both freezing cold and too hot to touch. The Milky Way.”

Snape hummed in response. Harry could tell he was pleased.

“Hey,” Harry suddenly asked. “Why _am_ I here? We’re nowhere near enough to each other to be making eye contact. And neither of us was using Legilimency. Right?”

Snape was silent for a moment. “The mind is a creature of habit,” he said in a low voice. “It wears the pattern of its travels deeper and deeper with each iteration. Think of one thing, and your mind will follow its paths to its familiar clusters of associations. The same is true of minds traversing foreign landscapes. I have forged a bridge to your mind through endless repetition. Stressed and under attack, your mind naturally followed that pathway back.”

“Oh,” Harry said, and then, “Sorry. About invading your mind, I mean.”

“You should be,” Snape replied. He didn’t sound the least bit angry. Harry couldn’t see his face, but he could see his silhouette against the sky. There was a lack of tension to the set of his shoulders, the curve of his back. Harry was struck by the thought that this was probably the only place Snape could allow himself to fully relax, behind the safety of his Occlumency shields.

Snape laid back down in the grass, right beside Harry. “I already have to deal with you in the daytime. At least allow me to sleep in peace.”

“It’s your own fault,” Harry informed him. “Three months of detention. You could have easily skipped the weekends.”

“We all have our burdens to bear.”

Harry snorted softly. “Yes, sir.” He stared up at the mosaic of stars above him. He thought about returning to his own mind, of the dreams waiting to ambush him with blood and fire. The serenity ached in his bones.

“Can I stay a little longer?” Harry asked in a soft whisper.

“Yes,” Snape answered. “Just a little.”

Harry woke up the next morning calm and refreshed. The scent of winter earth had settled in his lungs. And when he closed his eyes, he could still see the stars.

**Notes for the Chapter:**

> Thanks to astahfrith for a wonderful job beta'ing, as usual!
> 
> wooooo it's been a while, but HEY that's what happens when u have major depressive disorder woop woop. but hey, chapter is out, which means that chapter 7 is written and chapter 8 is in the process of being written!
> 
> and for my followers who care about subject, the next chapter of that is like.... a sixth done. more or less
> 
> thank you guys for all your support!! i hope this chapter makes your day a little better

**Author's Note:**

> before anything else - thank u so much astahfrith, for being the cheerleader for a fic that i wasn't sure would ever see the light of day. i wouldn't have been able to write half as much as i have without your enthusiasm for every new chap driving me. your editing skills are invaluable, and i'm lucky to have u as a beta.
> 
> HEY IT'S YA BOY back with a fic that literally no one asked for. but i wanted to worldbuild, and so hey, u get this. i'm actually writing a longfic that's 100% prose. that means i might get exhausted with it, but i've been really motivated to work on it for a while, so whatever.
> 
> I actually started this two years ago, and only recently picked it back up. this chap + chap 2 might seem a little different in style from the next 4+ chaps, and if so, that's why.
> 
> sorry to all my subscribers that get all sorts of random shit. i know u probably subscribed for the bnha. oops.
> 
> thank you so much for reading! hope you enjoyed.


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